Patent Publication Number: US-2010112888-A1

Title: Manufacturing method of barrier ribs of plasma display panel

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional application of and claims priority benefit of U.S. application Ser. No. 11/218,091, filed on Aug. 31, 2005, now allowed. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention generally relates to a display panel and a manufacturing method thereof. More particularly, the invention relates to a plasma display panel and a manufacturing method of barrier ribs thereof. 
     2. Description of Related Art 
     Flat panel displays serve as a communication interface between human and computers. At present, the flat panel displays include plasma displays, organic electro-luminescent displays (OELD) and liquid crystal displays (LCD). Among them, plasma displays have such advantages as big size, self-illuminance, wide-view angle, thinness and full color, and thus have the potential of becoming the mainstream flat panel display product in its next generation. 
     In general, barrier ribs of a plasma display not only constitute discharging spaces in the display area of a panel, but also extend into the non-display area of the panel to assist the assembly of the front substrate and the rear substrate.  FIG. 1A  is a schematic partial vertical view of the conventional plasma display panel, and  FIG. 1B  is a cross sectional view taken along line A-A′ in  FIG. 1A . As shown in  FIGS. 1A and 1B , the plasma display panel  100  is divided into a display area  104  and a non-display area  102  located in the periphery of the display area  104 . Barrier ribs  130  constitute multiple rectangle discharge spaces  132  in the display area  104  above the rear substrate  120  and extend multiple stripe leads  140  into the non-display area  102  to support the structure after assembling the front substrate (not shown) and the rear substrate  120 . 
     Early plasma display panels&#39; lower resolution and broader barrier ribs allow the stripe leads to provide enough structural strength against the loading pressure when printing the fluorescent material layer in the discharge spaces. However, as modern display panels require higher resolution, the breadth of the barrier ribs has to be relatively decreased. The narrowed stripe leads may not provide enough structural strength and can be damaged by the loading pressure in printing. In addition, the stripe leads may undergo heterogeneous thermal expansion in the following sintering process due to regular thickness of the barrier ribs. As a result, as exemplified in  FIG. 2 , leads  140  are peeled off from the surface of rear substrate  120 , and in  FIG. 3 , the surface of the stripe leads  140  is deformed. 
     In either of the situation, the front substrate and the rear substrate will not be able to fit during assembly since the stripe leads are deformed, and will result in crosstalk disturbance during display so the display quality will be reduced. 
     SUMMARY OF THE INVENTION 
     Accordingly, the invention is directed to providing a plasma display panel and a manufacturing method of the barrier ribs thereof, which has honeycomb supporting structures in the non-display area to improve the yield factor of assembling the front substrate and the rear substrate as so to improve the display quality. 
     The invention provides a plasma display panel, which is divided into a display area and a non-display area located in the periphery of the display area. The plasma display panel comprises a front substrate, a rear substrate, multiple barrier ribs, and multiple supporting ribs, wherein the front substrate and the rear substrate are parallel, and the barrier ribs are disposed between the front substrate and the rear substrate in the display area and constitute discharging spaces. In addition, the supporting ribs are disposed between the front substrate and the rear substrate in the non-display area and constitute a plurality of honeycomb supporting structures. 
     The invention further provides a manufacturing method of barrier ribs of a plasma display panel. First, a substrate, divided into a display area and a non-display area located in the periphery of the display area, is provided. Next, when a patterned barrier material layer forms on the substrate, the layer further constitutes discharging spaces in the display area and a plurality of honeycomb supporting structures in the non-display area. 
     In conclusion, the plasma display panel and the manufacturing method of barrier ribs thereof in the invention is directed to forming the honeycomb supporting structures in the non-display area while the discharging space is formed, wherein the honeycomb supporting structures can enhance the structural strength and prevent cracking, peeling, or bulging caused in conventional printing or sintering process so the yield factor of assembling the substrates can be improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
         FIG. 1A  is a schematic partial vertical view of the conventional plasma display panel. 
         FIG. 1B  is a cross sectional view taken along line A-A′ from  FIG. 1A . 
         FIG. 2  is a schematic drawing illustrating the stripe leads peeling off the rear substrate shown in  FIG. 1B . 
         FIG. 3  is a schematic drawing illustrating the bulged stripe leads shown in  FIG. 1B . 
         FIG. 4  is a partial perspective view of a plasma display panel in accordance with one embodiment of the invention. 
         FIG. 5  is a schematic vertical view of the plasma display panel shown in  FIG. 4 . 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
       FIG. 4  is a partial perspective view of the plasma display panel in the invention. As shown in  FIG. 4 , the plasma display  400  comprises a front substrate  410 , a rear substrate  420 , scan electrodes  412 , sustain electrodes  414 , address electrode  422 , barrier ribs  430 , and supporting ribs  440 . The scan electrodes  412  and the sustain electrodes  414  are disposed in pairs in the front substrate  410  and are covered with a dielectric layer  416  and a passivation layer  418 , which is made of MgO. In addition, the address electrodes  422 , the barrier ribs  430 , and the supporting ribs  440  are disposed in the rear substrate  420 , wherein the barrier ribs  430 , the front substrate  410  and the rear substrate constitute discharging spaces  432 . Each discharging space  432  is filled with discharge gas (not shown). The supporting ribs  440  constitute a plurality of honeycomb supporting structures  442  between the front substrate  410  and the rear substrate  420 . Besides, the discharging spaces  432  is covered with a fluorescent material layer  450 , and the scan electrodes  412  and the sustain electrodes  414  is crisscrossed by the address electrodes  422  at the discharging spaces  432 . When voltages are applied to the scan electrodes  412 , the sustain electrodes  414  and the address electrodes  422 , the discharging gas discharges and emits ultraviolet light to illuminate the fluorescent material layer  450  and eventually lights up the plasma display panel  400 . 
       FIG. 5  is a schematic vertical view of the plasma display panel described above. To better describe the characteristics in the invention, the front substrate including scan electrodes and sustain electrodes, and the address electrodes on the rear substrate are not shown in  FIG. 5 . 
     As shown in  FIG. 5 , the plasma display panel  400  is divided into a display area  404  and a non-display area  402 , which is located in the periphery of the display area  404 . The barrier ribs  430  and the supporting ribs  440  are disposed in the display area  404  and the non-display area  402  respectively. The barrier ribs  430  constitute discharging spaces  432 , and the supporting ribs  440  constitute a plurality of honeycomb supporting structures  442 . In an embodiment of the invention, the method of manufacturing the bather ribs  430  and supporting ribs  440  starts when the barrier material layer (not shown) in the rear substrate  420  takes shape. Then, a sandblasting process is performed on the barrier material layer inside a mask made of patterned photoresist layer (not shown). This is to constitute the barrier ribs  430  in the display area  404  and supporting ribs  440  in the non-display area  402  simultaneously. In another embodiment of the invention, the bather ribs  430  and the supporting ribs  440  can also be formed in the rear substrate  420  by multiple steps of screen printing. Furthermore, in still another embodiment of the invention, the patterned photoresist layer is formed on the rear substrate  420 , and then the bather ribs  430  and the supporting ribs  440  will be formed in an additive process in the region exposed by the patterned photoresist layer. 
     As shown in  FIG. 5 , the supporting structure of the invention can be modified according to the design parameters, such as resolution, of various panels. The relative dimensions of the supporting structure will be illustrated in the following paragraph by an example. Wherein, the length of the supporting structure  442  is a, the length of the short side of the discharging space  432  is b, and the width of the non-display area  402  is f. referring to  FIG. 5 , the supporting structure  442  is formed with the bather ribs  430  extending outward the display area  404 , and the included angle between two adjacent supporting ribs  440  is about 120 degrees. According to the foregoing geometric relation , a=b/√{square root over (3)}. In addition, the width f of the non-display area  402  is related to the length a of the supporting structure  442 . If the number of the supporting structure  442  is fixed, then the length a of the supporting structure  442  is proportional to the width f of the non-display area  402 . In other words, if the length a of the supporting structure  442  is fixed, then the number of the supporting structure  442  is proportional to the width f of the non-display area  402 . For example, in the embodiment shown in  FIG. 5 , f=4a. The following table lists practical values of the aforementioned geometric parameters according to plasma display panels with various resolutions. 
     
       
         
           
               
               
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 Dimension 
                 46 inch 
                 46 inch 
                 50 inch 
               
               
                   
                 Resolution 
                 852 * 480 
                 1280 * 768 
                 1366 * 768 
               
               
                   
                 a (um) 
                 227.5 
                 151.8 
                 147.2 
               
               
                   
                 b (um) 
                 394 
                 263 
                 255 
               
               
                   
                 f (um) 
                 909.9 
                 607.4 
                 588.9 
               
               
                   
                   
               
            
           
         
       
     
     As shown in  FIG. 5 , different from the conventional design of stripe leads, the invention provides multiple supporting structures  442  in the non-display area  402 , wherein the supporting structures  442  resemble the shape of a honeycomb. Because every two adjacent supporting ribs  440  have an included angle of approximately 120 degrees, each supporting rib  440  will receive the same loading pressure applied to the supporting structures  442  to achieve better structural strength. Therefore, the peeling or bulging of the supporting ribs  440  can be avoided in the following sintering process. In addition, the probability of the supporting structures  442  cracking up by loading pressure when forming the fluorescent material layer or undergoing other following process can also be prevented. 
     The main character of the invention is directed to changing the conventional design of the stripe leads to the honeycomb supporting structures to improve the structural strength. It should be noted that although the embodiment of the invention provides the honeycomb structures, in practice, the supporting structures can also be a rectangle, triangle, or multilateral closed structure to provide substantial improvement of structural strength. And changes in length, width, or thickness can also be made for the best result. 
     To sum up, the plasma display panel and the manufacturing method of the barrier ribs thereof in the invention is directed to forming the honeycomb supporting structures in the non-display area to provide better structural strength and avoid cracking, peeling, or bulging in the manufacturing process of prior art. Therefore, the yield factor of assembling the front substrate and the rear substrate can be improved and the crosstalk disturbance due to uneven assembly of the substrates can also be prevented for better display quality. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.