Abstract:
A plasma display panel and a manufacturing method thereof are disclosed. The plasma display panel includes discharge cells which are partitioned by an upper panel, a lower panel, and barrier ribs, and at least one groove which is formed on the upper panel correspondingly to the discharge cells.

Description:
[0001]    This application claims the benefit of Korean Patent Application No. 10-2006-0027857, filed on Mar. 28, 2006, which is hereby incorporated by reference as if fully set forth herein. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a plasma display panel, and more particularly, to an exhaust port that is formed on an upper panel of a plasma display panel. 
         [0004]    2. Discussion of the Related Art 
         [0005]    A plasma display panel has a structure in which barrier ribs provided between an upper panel and a lower panel form discharge cells. An inert gas containing a primary discharge gas, such as neon, helium, or a mixed gas thereof, and a small amount of xenon is charged in respective discharge cells. When the discharge happens with a high-frequency voltage, vacuum ultraviolet rays are generated by the inert gas and causes fluorescent substances between the barrier ribs to emit light so that an image is formed. Such a plasma display panel is highlighted as a next generation display device because the plasma display panel has an advantage of a thin and light constitution. 
         [0006]      FIG. 1  is a perspective view illustrating schematically the structure of a plasma display panel. As shown in  FIG. 1 , an upper panel  10  of the plasma display panel is provided with a plurality of sustain electrode pairs made up of scan electrodes  2  and sustain electrodes  3  that are arranged in pairs on a top glass substrate  1  which is an image display surface. And, a lower panel  20  is provided with a plurality of address electrodes  13  that are arranged on a bottom glass substrate  11  such that the address electrodes  13  cross the sustain electrode pairs. The upper panel  10  and the lower panel  20  are sealed parallel at a distance from each other. 
         [0007]    Barrier ribs  12  of a stripe type (or a well type) for forming a plurality of discharge spaces, i.e., discharge cells, are arranged in parallel with each other on the lower panel  20 . A plurality of address electrodes  13  for generating vacuum ultraviolet rays through an address discharge are disposed in parallel with the barrier ribs  12 . Red (R), green (G) and blue (B) fluorescent substances  14  which emit visible light for the image display at the address discharge are coated on the top surface of the lower panel  20 . And, a lower dielectric substance layer  15  is formed between the address electrodes  13  and the fluorescent substances  14  to protect the address electrodes  13 . 
         [0008]    Due to shock by positive ions at the point of discharge, an upper dielectric substance  4  provided at the upper panel  10  may be worn out, and a metal material like sodium (Na) may cause a short of the electrodes. To solve this problem, the upper dielectric substance  4  is coated with a protective film  5  of magnesium oxide (MgO) so as to protect the upper dielectric substance  4 . This is because magnesium oxide (MgO) endures the shock by the positive ions, has a high coefficient of secondary electron emission, and decreases a firing voltage. 
         [0009]    In the process of manufacturing the plasma display panel, an exhaust port is formed at the upper panel or the lower panel to exhaust impurities such as hydrogen (H 2 ) and carbon dioxide (CO 2 ) existing inside the discharge cells. Then, the discharge cells are made almost vacuous, and the inert gas containing helium is injected into the discharge cells. 
         [0010]      FIG. 2  is a view illustrating schematically an exhaust port of the conventional plasma display panel. As shown in  FIG. 2 , the upper panel  10  and the lower panel  20  are sealed to form the plasma display panel, and impurities existing in a discharge region  150  is exhausted outside through an exhaust port  170 . However, the exhaust process is not achieved smoothly. 
         [0011]    If the inert gas is charged into the discharge cells in the state that the impurities are not removed sufficiently, the impurities may adhere to the barrier ribs or the protective film and cause a change of properties of the elements. And, it may affect adversely discharge characteristics or brightness in the operation of the plasma display panel. 
       SUMMARY OF THE INVENTION 
       [0012]    Accordingly, the present invention is directed to a plasma display panel that substantially obviates one or more problems due to limitations and disadvantages of the related art. 
         [0013]    An object of the present invention is to provide a plasma display panel and a manufacturing method thereof that is capable of exhausting impurity gases existing inside discharge cells when sealing an upper panel and a lower panel of the plasma display panel. 
         [0014]    Another object of the present invention is to provide a plasma display panel and a manufacturing method thereof that is capable of maintaining properties of barrier ribs or a protective film and increasing discharge characteristics and brightness in the operation. 
         [0015]    Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
         [0016]    To achieve the object and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a plasma display panel comprises: discharge cells which are partitioned by an upper panel, a lower panel, and barrier ribs; and at least one groove which is formed on the upper panel correspondingly to the discharge cells. 
         [0017]    In another aspect of the present invention, a method for manufacturing a plasma display panel comprises: forming at least one groove on an upper panel; sealing the upper panel with a lower panel formed with barrier ribs; and exhausting a gas inside discharge cells partitioned by the upper panel, the barrier ribs and the lower panel through the groove. 
         [0018]    It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings: 
           [0020]      FIG. 1  is a perspective view illustrating schematically a structure of a conventional plasma display panel; 
           [0021]      FIG. 2  is a view illustrating schematically an exhaust port of the conventional plasma display panel; 
           [0022]      FIG. 3  is a view illustrating schematically a top substrate formed with grooves of a plasma display panel in accordance with a first embodiment of the present invention; 
           [0023]      FIG. 4  is a view illustrating mimetically a structure of discharge cells of the plasma display panel formed with the grooves in accordance with the first embodiment of the present invention; 
           [0024]      FIG. 5   a  is a perspective view illustrating schematically a top substrate formed with grooves of a plasma display panel in accordance with a second embodiment of the present invention; 
           [0025]      FIG. 5   b  is a sectional view seen from the B-side in  FIG. 5   a;    
           [0026]      FIG. 5   c  is a sectional view seen from the A-side in  FIG. 5   a;    
           [0027]      FIG. 6  is a sectional view illustrating schematically the plasma display panel formed with the grooves in accordance with the second embodiment of the present invention; and 
           [0028]      FIG. 7  is a flow chart illustrating a manufacturing method of the plasma display panel formed with the grooves in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0029]    Reference will now be made in detail to the preferred embodiments of the present invention associated with a plasma display panel and a manufacturing method thereof, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
         [0030]    A plasma display panel according to the present invention has a structure in which an upper panel is formed with grooves for exhausting impurities such as hydrogen (H 2 ) and carbon dioxide (CO 2 ) existing inside discharge spaces. The grooves are formed on a glass substrate of the upper panel or an upper dielectric substance, preferably formed on the surface opposing the discharge spaces. Therefore, the impurities existing inside the discharge spaces pass along the grooves and are exhausted outside of the plasma display panel through an exhaust port. 
         [0031]      FIG. 3  is a view illustrating schematically the top substrate formed with the grooves of the plasma display panel in accordance with a first embodiment of the present invention, and  FIG. 4  is a view illustrating mimetically the structure of discharge cells of the plasma display panel formed with the grooves in accordance with the first embodiment of the present invention. Hereinafter, the plasma display panel according to the first embodiment of the present invention will be described with reference to  FIGS. 3 and 4 . 
         [0032]    A top substrate  250  of the plasma display panel is formed with one or more grooves  250   a . The grooves  250   a  are connected to each other through first channels  250   b , and the first channels  250   b  are connected to each other through a second channel  250   c . The grooves  250   a  may not be formed on the top substrate  250  but formed on the upper dielectric substance in such a manner that the top substrate  250  is fabricated flat without the grooves and a portion of the upper dielectric substance is depressed to form the grooves  250   a.    
         [0033]    The grooves  250   a  may be formed to a depth of 20 to 1500 μm (50 μm for an XGA grade). Also, the grooves  250   a  may be formed at a width of 70 to 1000 μm (less than 700 μm, preferably 200 to 400 μm, for an XGA grade). The above width and depth of the grooves can be identically applied to the width and depth of the channels. 
         [0034]    The first channels  250   b  and the second channel  250   c  may be formed on the upper dielectric substance. Preferably, the first channels  250   b  and the second channel  250   c  are formed on the top substrate  250 . Also, the first channels  250   b  and the second channel  250   c  may be formed such that the surface of the top substrate  250  or the upper dielectric substance opposing the discharge spaces is depressed in a line type. 
         [0035]    In this embodiment, if the barrier ribs are shaped in a well type (not a stripe type) and form independent discharge cells for each red, green and blue, the grooves  250   a  may be formed independently corresponding to the respective discharge cells. The grooves  250   a  may be formed as a hexahedral, semispherical, trapezoidal, or parabolic shape. The impurities inside the discharge spaces are stored temporarily in the first channels  250   b  and the second channel  250   c , and exhausted outside of the plasma display panel through the first channels  250   b  and the second channel  250   c.    
         [0036]    The grooves  250   a  communicate with the exhaust port (not shown) through the first channels  250   b  and the second channel  250   c . The exhaust port is formed on the upper panel, and may be provided by one or more. The barrier ribs  230  depicted in  FIG. 4  have a well-type structure, and scan electrodes  260 Y and sustain electrodes  260 Z are formed on the top glass substrate correspondingly to the respective red, green and blue discharge cells. 
         [0037]    When the grooves  250   a , the first channels  250   b , and the second channel  250   c  are formed on the top substrate  250 , the scan electrodes  260 Y, the sustain electrodes  260 Z, the upper dielectric substance, and the protective film are formed on the top substrate  250  in order. Because the upper dielectric substance and the protective film are very thin when compared to the grooves  250   a , the first channels  250   b  and the second channel  250   c , the grooves and the channels can be formed in substantially the same shape on the top substrate contacting the discharge spaces even after the formation of the upper dielectric substance and the protective film. On the other hand, when the grooves  250   a , the first channels  250   b  and the second channel  250   c  are formed on the upper dielectric substance, the top substrate  250  is formed at a uniform thickness and then the upper dielectric substance is fabricated at uneven heights so as to form the grooves  250   a , the first channels  250   b , and the second channel  250   c.    
         [0038]      FIG. 7  is a flow chart illustrating a manufacturing method of the plasma display panel formed with the grooves in accordance with the present invention. Referring to  FIG. 7 , the manufacturing method of the plasma display panel according to the first embodiment of the present invention will now be described. 
         [0039]    The upper panel formed with the grooves are fabricated (S 710 ), and the lower panel formed with the barrier ribs are fabricated (S 720 ). The upper panel is formed such that the grooves and the first and second channels are formed on the top substrate opposing the discharge regions. The grooves are connected to each other through the first and second channels. When the upper panel and the lower panel formed with the well-type barrier ribs are sealed, it is preferable to divide the grooves respectively and form the respective grooves on the top glass correspondingly to the respective discharge cells. It is preferable to form the grooves and the first and second channels by putting the top glass into a mold before plastic working. In particular, it is preferred that the grooves are formed as a hexahedral, semispherical, trapezoidal, or parabolic shape. 
         [0040]    Thereafter, the scan electrodes, the sustain electrodes, the upper dielectric substance and the protective film are formed in order on the top substrate formed with the grooves and the first and second channels, thereby completing the fabrication of the upper panel of the plasma display panel. It is preferable to form the scan electrodes and the sustain electrodes using an off-set method or a printing method. Further, the upper dielectric substance and the protective film may be formed using a sputtering method or an electron beam deposition method. Accordingly, the shapes of the grooves and the first and second channels formed on the top substrate can be kept substantially identical. 
         [0041]    Subsequently, the lower panel formed with the barrier ribs and the upper panel fabricated as above are sealed (S 730 ). Preferably, a seal frit is used as a sealing material. The seal frit is applied with plastic and heating workings. Thereafter, the impurities are exhausted through the grooves and the channels (S 740 ). Finally, in order to increase an efficiency of the plasma discharge, an inert gas containing helium (He), neon (Ne), or xenon (Xe) is injected into the discharge cells of the plasma display panel (S 750 ). 
         [0042]    Remaining processes except for the aforesaid processes are identical to a typical manufacturing method of the plasma display panel. 
         [0043]    An operational effect of the plasma display panel according to the first embodiment of the present invention and the manufacturing method thereof will now be described. 
         [0044]    When the sealing process of the upper panel and the lower panel is terminated, the impurities inside the discharge spaces are exhausted through the grooves and the first and second channels, and then the discharge gas can be injected into the discharge cells. The grooves and the first and second channels may be formed on the upper dielectric substance (not on the top substrate). In this case, the sustain electrode pairs are formed on the flat top substrate, and a partial layer of the upper dielectric substance layer is formed using an electron beam deposition method or a sputtering method. And, after a taping working, the remaining layer of the upper dielectric substance layer is deposited so as to form the shapes of the grooves and the first and second channels. Thereafter, the protective film of MgO is coated on the upper dielectric substance layer formed with the grooves and the first and second channels. 
         [0045]      FIG. 5   a  is a perspective view illustrating schematically a top substrate formed with grooves of a plasma display panel in accordance with a second embodiment of the present invention,  FIGS. 5   b  and  5   c  are sectional views seen from the B-side and the A-side in  FIG. 5   a , respectively, and  FIG. 6  is a sectional view illustrating schematically the plasma display panel formed with the grooves in accordance with the second embodiment of the present invention. 
         [0046]    This embodiment has a structural feature that grooves  250   d  are formed on the upper panel  250  in a line type. It is preferred that the grooves  250   d  are disposed in parallel with the stripe-type barrier ribs formed on the lower panel. The grooves  250   d  may be formed to a depth of 20 to 1500 μm (50 μm for an XGA grade). Also, the grooves  250   d  may be formed at a width of 70 to 1000 μm (less than 700 μm, preferably 200 to 400 μm, for an XGA grade). 
         [0047]    The grooves  250   d  may be connected to channels  250   f  at both ends, so as to exhaust the impurity gas inside the discharge regions. The width and the depth of the channels  250   f  are equal to the width and the depth of the grooves  250   d . The depth h refers to a height difference between a surface  250   e  where the grooves  250   d  are not formed and the grooves  250   d , and the width w refers to the shortest distance from one of the grooves  250   d  to the other one of the grooves  250   d.    
         [0048]    After the grooves  250   d  and the channels  250   f  are formed on the top substrate  250 , the scan electrodes  260 Y, the sustain electrodes  260   z , the upper dielectric substance  280 , and the protective film  290  are formed on the top substrate  250  in order. Accordingly, the grooves  250   d  and the channels  250   f  are formed in substantially the same shape on the upper panel contacting the discharge spaces. The grooves  250   d  are formed on the upper panel opposing the discharge spaces, so as to have a function of forming a passage for exhausting the impurities above the discharge spaces. In this embodiment, if the barrier ribs are formed as a well type, it is preferable to form the grooves  250   d  on the upper panel correspondingly to the horizontal ribs. Also, the grooves and/or the channels may not be formed on the top substrate  250  but formed on the upper dielectric substance  280  in such a manner that the upper dielectric substance  280  is fabricated at uneven heights. 
         [0049]      FIG. 7  is the flow chart illustrating the manufacturing method of the plasma display panel formed with the grooves in accordance with the present invention. Referring to  FIG. 7 , the manufacturing method of the plasma display panel according to the second embodiment of the present invention will now be described. 
         [0050]    First, the upper panel formed with the grooves are fabricated (S 710 ), and the lower panel formed with the barrier ribs are fabricated (S 720 ). The upper panel is fabricated such that the grooves and the channels are formed on the top substrate opposing the discharge regions. The grooves are connected to the channels. When the upper panel and the lower panel formed with the stripe-type barrier ribs are sealed, it is preferable to form the grooves parallel with the respective discharge regions. When the upper panel and the lower panel formed with the well-type barrier ribs are sealed, it is preferable to form the grooves parallel with the horizontal ribs. Also, the grooves are connected to the channels at both ends, so that the impurities inside the discharge regions can be exhausted through the exhaust port via the channels. 
         [0051]    Thereafter, the scan electrodes, the sustain electrodes, the upper dielectric substance and the protective film are formed in order on the top glass formed with the grooves and the channels, thereby completing the fabrication of the upper panel of the plasma display panel. It is preferable to form the scan electrodes and the sustain electrodes using an off-set method or a printing method. And, it is preferable to form the upper dielectric substance and the protective film using a sputtering method or an electron beam deposition method. Accordingly, the shapes of the grooves and the channels formed on the top substrate can be kept substantially identical. The grooves and the channels may be formed on the upper dielectric substance (not on the top substrate). In this case, the sustain electrode pairs are formed on the flat top substrate, and a partial layer of the upper dielectric substance layer is formed using an electron beam deposition method or a sputtering method. And, after a taping working, the remaining layer of the upper dielectric substance layer is deposited so as to form the shapes of the grooves and the channels. Thereafter, the protective film of MgO is coated on the upper dielectric substance layer formed with the grooves and the channels. 
         [0052]    Subsequently, the lower panel formed with the barrier ribs and the upper panel fabricated as above are sealed (S 730 ). Preferably, a seal frit is used as a sealing material. The seal frit is applied with plastic and heating workings. Thereafter, the impurities are exhausted through the grooves and the channels (S 740 ). Finally, in order to increase an efficiency of the plasma discharge, An inert gas containing helium (He), neon (Ne), or xenon (Xe) is injected into the discharge cells of the plasma display panel (S 750 ). 
         [0053]    Remaining processes except for the aforesaid processes are identical to a typical manufacturing method of the plasma display panel. 
         [0054]    An operational effect of the plasma display panel according to the second embodiment of the present invention and the manufacturing method thereof will now be described. 
         [0055]    When the sealing process of the upper panel and the lower panel is terminated, the impurities inside the discharge spaces are exhausted through the exhaust port via the grooves and the channels, and then the discharge gas can be injected into the discharge cells. 
         [0056]    It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.