Patent Abstract:
A plasma display panel includes a first substrate, a second substrate mounted opposing the first substrate with a predetermined gap therebetween to thereby form a vacuum assembly, and barrier ribs formed between the first substrate and the second substrate, the barrier ribs defining discharge cells. The barrier ribs are formed so as to provide radial exhaust paths for each of the discharge cells. Moreover, the barrier ribs are configured dimensioned and arranged so as to maximize the exhaust efficiency of the plasma display panel.

Full Description:
CLAIM OF PRIORITY  
         [0001]    This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application entitled PLASMA DISPLAY PANEL filed with the Korean Industrial Property Office on 17 Dec. 2002 and there duly assigned Serial No. 2002-0080804, and an application entitled PLASMA DISPLAY PANEL filed with the Korean Industrial Property Office on Jan. 15, 2003 and there duly assigned Serial No. 2003-0002682.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Technical Field  
           [0003]    The present invention relates to a plasma display panel and, more particularly, to barrier ribs of a plasma display panel.  
           [0004]    2. Related Art  
           [0005]    A plasma display panel (PDP) typically includes barrier ribs that define discharge cells. The two main types of barrier ribs are closed barrier ribs and open barrier ribs. The open barrier ribs are generally formed in a stripe configuration. Since discharge cells formed between such stripe-type barrier ribs are in communication (i.e., the discharge cells between each pair of adjacent barrier ribs are in communication), exhaust of the PDP and sealing of discharge gas within the PDP are relatively easily performed during manufacture.  
           [0006]    With the closed barrier ribs, on the other hand, the discharge cells are not in communication. That is, the barrier ribs are formed into individual units having a quadrilateral, hexagonal, or other shape. With the closed barrier ribs, the discharge cells are separately formed for each pixel, and phosphor material is formed over all inner surfaces of barrier ribs that form each pixel.  
           [0007]    In the first PDPs that utilized such closed barrier ribs, a gap formed between a distal end of the barrier ribs and the substrate opposing the substrate on which the barrier ribs are formed was used as an exhaust path. The gap was formed by adjusting the height of the barrier ribs or by forming depressions at predetermined locations of distal end areas of the barrier ribs. However, because of the minimal size of the gap, the resulting exhaust resistance necessitated the use of a significant amount of time to exhaust the PDP. This reduced overall manufacturing efficiency.  
           [0008]    Various configurations have been disclosed to overcome these problems. For example, Japanese Laid-Open Patent No. Heisei 4-274141 discloses a structure in which open stripe-type barrier ribs and closed lattice-type barrier ribs are combined to reduce exhaust resistance. However, with such a combinational structure, the process of forming each barrier rib on the substrate during PDP manufacture is complicated. With this structure, productivity is reduced to such an extent that mass production is made difficult.  
           [0009]    Japanese Laid-Open Patent No. Heisei 2002-83545 discloses a PDP in which closed barrier ribs are formed using a material that has a heat shrink property. The barrier ribs are formed having areas of lesser height that function as exhaust paths to thereby form a mesh-type structure of the exhaust paths. Although it is claimed that such a barrier rib structure reduces exhaust resistance during the exhaust process, in practice, there is a limited number of paths through which exhaust may occur as a result of the mesh configuration. This may result in insufficient exhaust of the PDP.  
         SUMMARY OF THE INVENTION  
         [0010]    The present invention provides a plasma display panel including barrier ribs that maximize exhaust efficiency.  
           [0011]    More particularly, the present invention provides a plasma display panel including barrier ribs that enable improvements in brightness through the efficient use of discharge cells.  
           [0012]    In one embodiment, the present invention provides a plasma display panel including a first substrate, a second substrate mounted opposing the first substrate with a predetermined gap therebetween to thereby form a vacuum assembly, and barrier ribs formed between the first substrate and the second substrate, the barrier ribs defining discharge cells. Radial exhaust paths are formed in the barrier ribs for each of the discharge cells.  
           [0013]    The discharge cells are formed in a closed configuration by the barrier ribs, and the discharge cells are arranged in a lattice pattern or a delta pattern.  
           [0014]    In another embodiment, the present invention is a plasma display panel including a first substrate, a second substrate mounted opposing the first substrate with a predetermined gap therebetween to thereby form a vacuum assembly, and barrier ribs formed on the second substrate and extending a predetermined distance in a direction toward the first substrate, the barrier ribs defining discharge cells. A plan view of the barrier ribs is such that, if imaginary lines are formed bisecting distal end surfaces of the barrier ribs, the imaginary lines form a plurality of multilateral shapes that encompass each of the discharge cells to thereby form the discharge cells into the multilateral shapes. Also, if a radius of a first inscribed circle drawn in areas of the barrier ribs corresponding to corner portions of the multilateral shapes of the discharge cells is R, and a radius of a second inscribed circle drawn in areas corresponding to predetermined points between the corner portions of the multilateral shapes of the discharge cells is r, the following condition is satisfied: 
           R&gt;r. 
           [0015]    Alternatively, the barrier ribs may be formed so as to satisfy the following condition: 
           R&gt;2r. 
           [0016]    The barrier ribs are made of a material that has a heat shrink property, and widths of the distal end surfaces of the barrier ribs vary, in a continuous manner or in stages, along a direction in which the barrier ribs are formed.  
           [0017]    Further, exhaust paths are formed in the barrier ribs such that one of the exhaust paths is formed in areas of the barrier ribs corresponding to each side of the multilateral discharge cells. The exhaust paths are formed in the distal ends of the barrier ribs.  
           [0018]    The plasma display panel further includes sub exhaust paths formed in areas of the barrier ribs where corner portions of the multilateral shapes of the discharge cells converge. The sub exhaust paths are realized by exhaust grooves formed in the barrier ribs.  
           [0019]    In another embodiment, the present invention is a plasma display panel including a first substrate, a second substrate mounted opposing the first substrate with a predetermined gap therebetween to thereby form a vacuum assembly, and barrier ribs formed on the second substrate and extending a predetermined distance in a direction toward the first substrate, the barrier ribs defining discharge cells. A plan view of the barrier ribs is such that, if imaginary lines are formed bisecting distal end surfaces of the barrier ribs, the imaginary lines form a plurality of multilateral shapes that encompass each of the discharge cells to thereby form the discharge cells into the multilateral shapes.  
           [0020]    Also, the height of the barrier ribs, measured from where they are formed on the second substrate to the distal end of the same, is greater at areas corresponding to corner portions of the multilateral shapes of the discharge cells than at areas between the corner portions of the multilateral shapes of the discharge cells.  
           [0021]    The height of the barrier ribs is at a maximum at areas corresponding to the corner portions of the multilateral shapes of the discharge cells, and the height of the barrier ribs is at a minimum at predetermined points between the corner portions of the multilateral shapes of the discharge cells.  
           [0022]    A width of the distal ends of the barrier ribs at areas corresponding to the corner portions of the multilateral shapes of the discharge cells is greater than the width of the distal ends of the barrier ribs at areas between the corner portions of the multilateral shapes of the discharge cells.  
           [0023]    Further, the heights of the barrier ribs vary in a continuous manner starting from where the heights are maximum and decreasing until reaching the minimum heights.  
           [0024]    The present invention is more specifically described in the following paragraphs by reference to the drawings attached only by way of example. Other advantages and features will become apparent from following description and from the appended claims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]    A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein:  
         [0026]    [0026]FIG. 1 is a partial exploded perspective view of a plasma display panel according to a first embodiment of the present invention;  
         [0027]    [0027]FIG. 2 is a plan view showing a structure of barrier ribs of FIG. 1;  
         [0028]    [0028]FIGS. 3A and 3B are sectional views taken along lines A-A and B-B of FIG. 2;  
         [0029]    [0029]FIG. 4 is a plan view showing a structure of barrier ribs according to a second embodiment of the present invention;  
         [0030]    [0030]FIGS. 5, 6, and  7  are plan views showing a structure of barrier ribs according to a third embodiment of the present invention;  
         [0031]    [0031]FIG. 8 is a partial exploded perspective view of a plasma display panel according to a fourth embodiment of the present invention;  
         [0032]    [0032]FIG. 9 is an enlarged perspective view of a sub exhaust path of FIG. 8; and  
         [0033]    [0033]FIG. 10 is a partial plan view of a plasma display panel according to a fifth embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0034]    Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.  
         [0035]    [0035]FIG. 1 is a partial exploded perspective view of a plasma display panel according to a first embodiment of the present invention, FIG. 2 is a plan view showing a structure of barrier ribs of FIG. 1, and FIGS. 3A and 3B are sectional views taken along lines A-A and B-B of FIG. 2.  
         [0036]    With reference to the drawings, the plasma display panel (PDP) according to the first embodiment of the present invention includes a first substrate  10  and a second substrate  12  opposing one another with a predetermined gap therebetween. A vacuum assembly is formed by the combination of the first substrate  10  and the second substrate  12 .  
         [0037]    Address electrodes  14  are formed in a predetermined pattern (e.g., a stripe pattern) and at predetermined intervals on the second substrate  12 . A first dielectric layer  16  is formed on the second substrate  12  and covers the address electrodes  14 . Further, barrier ribs  18  are formed on the first dielectric layer  16  and in a predetermined pattern to define a plurality of discharge cells  17 .  
         [0038]    In the first embodiment, the barrier ribs  18  are made of a glass material having a low melting point. Regarding a plan view formation of the barrier ribs  18 , with reference to FIGS. 1 and 2, in a state where imaginary lines L are formed bisecting distal end surfaces of the barrier ribs  18 , the imaginary lines L form a plurality of multilateral shapes that encompass each of the discharge cells  17 . In the first embodiment, the imaginary lines L are formed into a plurality of quadrilateral shapes.  
         [0039]    The barrier ribs  18  include row sections  18   a  extending in a direction substantially perpendicular to the direction in which the address electrodes  14  are formed, and column sections  18   b  extending in a direction substantially parallel to the direction in which the address electrodes  14  are formed. Areas where the row sections  18   a  and the column sections  18   b  intersect, that is, areas of the barrier ribs  18  between four adjacent discharge cells  17 , occupy a greater space than other areas of the barrier ribs  18 . The formation of the barrier ribs  18 , and, in particular, the relative widths of the barrier ribs  18 , will be described in greater detail below.  
         [0040]    As an example, areas of the barrier ribs  18  between four adjacent discharge cells  17  are the greatest among all areas of the barrier ribs  18 , while areas of the barrier ribs  18  corresponding to centers of long sides and short sides of adjacent discharge cells  17  are the smallest among all areas of the barrier ribs  18 . In particular, a radius R of a first inscribed circle C 1  (see FIG. 2) drawn in one of the areas of the barrier ribs  18  between four adjacent discharge cells  17  is greater than a radius r of a second inscribed circle C 2  (see FIG. 2) drawn in areas corresponding to the center of the long sides and short sides of adjacent discharge cells  17 . That is, these radii R and r satisfy the condition R&gt;r, and more preferably satisfy the condition R&gt;2r.  
         [0041]    With reference to FIGS. 3A and 3B, areas where the second inscribed circles C 2  are drawn, that is, areas of the barrier ribs  18  corresponding to centers of the long sides and short sides of adjacent discharge cells  17  with the smallest widths, have a height H1 that is the smallest among all areas of the barrier ribs  18 , while areas of the barrier ribs  18  between four adjacent discharge cells  17  have a height H2 that is the greatest among all areas of the barrier ribs  18 .  
         [0042]    With this configuration, gaps of predetermined dimensions are formed between the first substrate  10  and the distal ends of the row sections  18   a  and the column sections  18   b  of the barrier ribs  18  by the difference in the heights H1 and H2. Preferably, the difference in the heights H1 and H2 is between 5 and 10 μm. These gaps function as exhaust paths P through which air inside the PDP travels when forming a vacuum in the same during manufacture. As a result, radial paths P are provided for each of the discharge cells  17 . In the first embodiment, four exhaust paths P are provided for each discharge cell  17 .  
         [0043]    The barrier ribs  18  are formed by a sandblast process, which is commonly used in the manufacture of PDPs. If a minimum width of the barrier ribs  18  that can be formed using the sandblast process is m, the radius r of the second inscribed circle C 2  described above satisfies the condition: 
         2r&gt;m. 
         [0044]    Further, with reference to FIG. 2, the width of the row sections  18   a  and the column sections  18   b  of the barrier ribs  18  may be continuously (i.e., not abruptly and not in steps) made larger as the distance from their centers (where the inscribed circles C 2  are formed) is increased. Also, with reference to FIGS. 3A and 3B, the heights of the row sections  18   a  and the column sections  18   b  may be continuously reduced starting from areas thereof where the heights are H2 and moving toward areas thereof where the heights are H1.  
         [0045]    The barrier ribs  18  structured as described above are produced according to the following manufacturing method of the present invention.  
         [0046]    First, in a state where the address electrodes  14  and the first dielectric layer  16  are formed on the second substrate  12 , a barrier rib material layer of a predetermined thickness is realized through a paste, which is formed by uniformly mixing a vehicle and a glass powder having a low melting point, and the barrier rib material layer is formed on the first dielectric layer  16  using a screen printing method or a laminate method. The glass powder of a low melting point may be made, for example, of a material containing 50˜60 wt % of Pbo, 5˜10 wt % of B 2 O 3 , 10˜20 wt % of SiO 2 , 15˜25 wt % of Al 2 O 2 , and 5% or less of CaO.  
         [0047]    Following the drying of the barrier rib material layer, a photosensitive dry film is formed or a resist material is deposited. Then, using a photolithography process that includes exposure and development, a cut mask is formed in a lattice pattern corresponding to the desired shape of barrier ribs. The dimensions of the mask pattern are set to be greater than the desired dimensions of the barrier ribs since thermal contraction of the barrier rib material layer occurs.  
         [0048]    Next, using a sandblast process, non-masked portions of the barrier rib material layer are removed until the dielectric layer is exposed. Heating and baking are then performed to thereby complete the formation of the barrier ribs.  
         [0049]    The cut mask has a pattern corresponding to the various shapes of the barrier ribs  18  as described above.  
         [0050]    Red, green, and blue phosphor layers  20 R,  20 G, and  20 B (see FIG. 1) are deposited on areas of the first dielectric layer  16  positioned within the discharge cells  17  and on inner surfaces of the barrier ribs  18  within the discharge cells  17  to thereby form corresponding pixels (i.e., R, G, and B pixels). In the first embodiment, the discharge cells  17  are arranged in a lattice pattern wherein each of the discharge cells is individually formed in fully closed units by the barrier ribs  18 .  
         [0051]    Further, formed on a surface of the first substrate  10 , opposing the second substrate  12 , are discharge sustain electrodes  22  that include common electrodes  22   a , scanning electrodes  22   b , and bus electrodes  22   c  formed on each of the common electrodes  22   a  and the scanning electrodes  22   b  The common electrodes  22   a  and the scanning electrodes  22   b  are made of a transparent material, such as indium tin oxide (ITO), and the bus electrodes  22   c  are made of a conductive material, such as silver (Ag) or gold (Au).  
         [0052]    The discharge sustain electrodes  22  are formed in a direction substantially perpendicular to the direction in which the address electrodes  14  are formed. A second dielectric layer  24  is formed on the first substrate  10  covering the discharge sustain electrodes  22 , and a protective layer made of MgO is formed over the second dielectric layer  24 . The protective layer  26  acts to protect the discharge sustain electrodes  22 , and functions also to aid discharge by emitting secondary electrons.  
         [0053]    In the PDP having the closed barrier rib structure as described above, there are provided radial exhaust paths P for each of the discharge cells  17  such that exhaust efficiency is significantly improved over the prior art.  
         [0054]    [0054]FIG. 4 is a plan view showing the structure of barrier ribs according to a second embodiment of the present invention. Barrier ribs  28  according to the second embodiment have the basic structure of the barrier ribs of the first embodiment. However, row sections  28   a  of the barrier ribs  28  that define discharge cells  27  are positioned differently. In particular, the row sections  28   a  of the barrier ribs  28  of adjacent discharge cells  27  (i.e., adjacent in a direction in which the row sections  28   a  are formed) are offset and not aligned as in the first embodiment. As a result, the discharge cells  27  defined by the barrier ribs  28  are arranged in a delta pattern.  
         [0055]    [0055]FIGS. 5, 6, and  7  are plan views showing the structure of barrier ribs according to a third embodiment of the present invention. FIG. 5 shows a structure in which imaginary lines L bisecting distal end surfaces of barrier ribs  38  are formed into a plurality of hexagonal shapes. Stated differently, the barrier ribs  38  are formed to define a plurality of discharge cells  37  such that the discharge cells  37  are formed as individual, closed units in the shape of a hexagon or a similar form. As a result of this configuration, the discharge cells  37  may be arranged in a delta configuration.  
         [0056]    In the third embodiment, areas of the barrier ribs  38  between any three, mutually adjacent discharge cells  37  occupy the largest area and have the greatest height when compared to other areas of the barrier ribs  38 , that is, main sections  38   a  of the barrier ribs  38 . This results in the formation of exhaust paths in the main sections  38   a  of the barrier ribs  38 . Since there is a larger number of exhaust paths for each of the discharge cells  37  than in the first embodiment, an even greater improvement in exhaust efficiency is realized.  
         [0057]    The basic configuration of FIGS. 5, 6 and  7  shows the barrier ribs  38  defining the discharge cells  37  such that the discharge cells  37  are formed as closed, 12-sided individual units. As shown in FIG. 6, the twelve sides forming each of the discharge cells  37  are substantially equal in length, and the barrier ribs  38  are placed in relation to one another such that the main sections  38   a  between adjacent discharge cells  37  have a width that increases as the distance from the center of the main sections  38   a  increases.  
         [0058]    In FIG. 7, the twelve sides forming each of the discharge cells  37  are not equal in length. That is, the sides that form the main sections  38   a  are longer than the sides in areas where three, mutually adjacent discharge cells  37  converge. Therefore, the widths of the barrier ribs  38  along the main sections  38   a  remain constant.  
         [0059]    [0059]FIG. 8 is a partial exploded perspective view of a plasma display panel according to a fourth embodiment of the present invention. Like reference numerals will be used for elements of the fourth embodiment identical to those of the first embodiment.  
         [0060]    The PDP of the fourth embodiment of the present invention utilizes the same basic structure as the PDP of the first embodiment. However, sub exhaust paths  40  are formed at areas where the row sections  18   a  and the column sections  18   b  intersect, that is, at areas of the barrier ribs  18  between four adjacent discharge cells  17 .  
         [0061]    The sub exhaust paths  40  are formed to enable communication between adjacent discharge cells  17  to thereby improve the exhaust process. With reference also to FIG. 9, the sub exhaust paths  40  are realized by forming exhaust grooves in the barrier ribs  18 . The sub exhaust paths  40  may be formed in a simple manner using an etching process. As an example, the exhaust grooves may be formed to a width of 10˜100 μm and a depth of 10˜130 μm.  
         [0062]    With the PDP of the fourth embodiment, in addition to the radial exhaust paths formed by the particular configuration of the row sections  18   a  and the column sections  18   b  of the barrier ribs  18  as described with reference to the first embodiment, the sub exhaust paths  40  act to even further improve exhaust efficiency.  
         [0063]    [0063]FIG. 10 is a partial plan view of a plasma display panel according to a fifth embodiment of the present invention. In the fifth embodiment, sub exhaust paths  50  are formed on barrier ribs  48  in the case where the barrier ribs  48  are formed to realize a delta pattern of discharge cells. Although the sub exhaust paths  50  are formed at each corner area between adjacent discharge cells, it is also possible to form the sub exhaust paths  50  at other selective locations.  
         [0064]    While the present invention has been illustrated by the description of embodiment thereof, and while the embodiments have been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the special details, representative apparatus and method, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the sprit and scope of the general inventive concept.

Technology Classification (CPC): 7