Abstract:
A plasma display panel includes a first substrate and a second substrate opposing one another with a predetermined gap therebetween. Address electrodes are formed on the second substrate. Barrier ribs are mounted in the gap between the first substrate and the second substrate to define a plurality of discharge cells. Phosphor layers are formed in each of the discharge cells. Discharge sustain electrodes are formed in a direction intersecting the address electrodes and paired such that each of the discharge cells is in communication with a pair of the discharge sustain electrodes. Each of the discharge sustain electrodes include extension sections that extend into the discharge cells such that a pair of opposing extension sections is formed in each of the discharge cells. Distal ends of each of the extension sections extended from at least one of each pair of the bus electrodes are formed having a concave section.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and the benefit of Korea Patent Application No. 2002-0084984 filed on Dec. 27, 2002, Korea Patent Application No. 2003-0050278 filed on Jul. 22, 2003 and Korea Patent Application No. 2003-0052598 filed on Jul. 30, 2003, all filed in the Korean Intellectual Property Office, the entire contents of which are each incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     (a) Field of the Invention 
     The present invention relates to a plasma display panel, and more particularly, to a surface discharge-type plasma display panel having an electrode structure in which a pair of discharge sustain electrodes that generate display discharge is mounted corresponding to each discharge cell between two substrates. 
     (b) Description of the Related Art 
     A plasma display panel (PDP) is typically a display device in which ultraviolet rays generated by the discharge of gas excite phosphors to realize predetermined images. As a result of the high resolution possible with PDPs (even with large screen sizes), many believe that they will become a major, next generation flat panel display configuration. 
     In a conventional PDP, with reference to  FIG. 5 , address electrodes  51  are formed along one direction (direction X in the drawing) on second substrate  50 . Dielectric layer  53  is formed over an entire surface of second substrate  50  on which address electrodes  51  are formed such that dielectric layer  53  covers address electrodes  51 . Barrier ribs  55  are formed on dielectric layer  53  in a line pattern and at locations between address electrodes  51 . Red, green, and blue phosphor layers  57  are formed between barrier ribs  55  are. 
     First substrate  60  is provided opposing second substrate  50 . Discharge sustain electrodes  64  are formed on a surface of first substrate  60  facing second substrate  50 . Each of discharge sustain electrodes  64  includes a pair of transparent electrodes  62  and a pair of bus electrodes  63 . Transparent electrodes  62  and bus electrodes  63  are arranged in a direction substantially perpendicular to address electrodes  51  of first substrate  60  (i.e., along direction Y). Dielectric layer  66  is formed over an entire surface of first substrate  60  on which discharge sustain electrodes  64  are formed such that dielectric layer  66  covers discharge sustain electrodes  64 . MgO protection layer  68  is formed covering dielectric layer  66 . 
     Areas between where address electrodes  51  of second substrate  50  and discharge sustain electrodes  64  of first substrate  60  intersect become areas that form discharge cells. 
     An address voltage Va is applied between address electrodes  51  and discharge sustain electrodes  64  to perform address discharge. Then a sustain voltage Vs is applied between a pair of discharge sustain electrodes  64  to perform sustain discharge. Ultraviolet rays generated at this time excite corresponding phosphor layers  57  such that visible light is emitted through first substrate  60 , which is transparent, to realize the display of images. 
     Discharge sustain electrodes  64  will be described in greater detail with reference now to  FIG. 6 . Transparent electrodes  62  are formed substantially perpendicular to the direction of barrier ribs  55  as described above. Transparent electrodes  62  comprising each pair that form discharge sustain electrodes  64  are provided at a predetermined distance from each other. That is, each pair of transparent electrodes  62  occupies a predetermined space along direction X. Also, a predetermined spacing is used between adjacent pairs of transparent electrodes  62 . Bus electrodes  63  enhance electric conductivity and are formed such that one of bus electrodes  63  is provided along a long edge of each of transparent electrodes  62  to thereby complete the formation of discharge sustain electrodes  64 . 
     In an alternative conventional configuration, with reference to  FIG. 7 , discharge sustain electrodes  74  are formed including a pair of bus electrodes  73  provided substantially perpendicular to barrier ribs  55  (along direction Y), and transparent electrodes  72  formed extending from bus electrodes  73  to be positioned within each discharge cell. Transparent electrodes  72  are formed in a T-shape with the base of the “T” connected to bus electrodes  73  as shown in the figure. 
     However, with respect to the structure shown in  FIGS. 5 and 6  in which each pair of transparent electrodes  62  occupies a predetermined space along direction X, since a uniform field is not formed over the entire surface of transparent electrodes  62  when a voltage is applied to discharge sustain electrodes  64  to effect discharge, many unnecessary areas of transparent electrodes  62  result which contribute little to discharge. In addition to reducing discharge efficiency within the discharge cells, these areas reduce brightness by screening a significant region of the discharge cells. 
     Further, when forming transparent electrodes  72  in a T-shape as shown in  FIG. 7 , a situation results where discharge is concentrated at corner areas of transparent electrodes  72 . This prevents the uniform spreading of discharge within the discharge cells. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention a plasma display panel is provided in which the distribution of discharge within discharge cells is analyzed to optimize the formation of discharge sustain electrodes such that a discharge initialization voltage is reduced and discharge efficiency is improved. 
     In one embodiment, the present invention involves a plasma display panel which includes a first substrate and a second substrate opposing one another with a predetermined gap therebetween. Address electrodes are formed on the second substrate. Barrier ribs are mounted in the gap between the first substrate and the second substrate to define a plurality of discharge cells. Phosphor layers are formed in each of the discharge cells. Discharge sustain electrodes are formed in a direction intersecting the address electrodes and paired such that each of the discharge cells is in communication with a pair of the discharge sustain electrodes. Each of the discharge sustain electrodes include extension sections that extend into the discharge cells such that a pair of opposing extension sections is formed in each of the discharge cells. Distal ends of each of the extension sections extended from at least one of each pair of the discharge sustain electrodes are formed having a concave section. 
     In an exemplary embodiment, the concave section may be formed in substantially a center of the distal ends of the extension sections, and the concave section of the extension sections is connected to areas at its peripheries through curved, smoothly rounded sections. 
     Convex sections may be formed to both sides of the concave section. 
     Each of the extension sections of the discharge sustain electrodes may be formed such that at least one long side is inwardly formed away from an adjacent barrier rib for a predetermined length of the extension sections. Also, each of the extension sections of the discharge sustain electrodes is formed such that a width in the direction intersecting the address electrodes is decreased as a distance from a center of the discharge cells is increased. 
     The discharge sustain electrodes may include bus electrodes formed in a direction intersecting the address electrodes and paired such that each of the discharge cells is in communication with a pair of the bus electrodes, and extension electrodes formed extended from the bus electrode within each of the discharge cells such that a pair of opposing extension electrodes is formed in each of the discharge cells. Distal ends of each of the extension electrodes are extended from at least one of each pair of the bus electrodes and are formed having a concave section. 
     The extension electrodes may be transparent. Also, each of the extension electrodes of the discharge sustain electrodes is formed such that a width in the direction intersecting the address electrodes is decreased as a distance from a center of the discharge cells is increased. 
     In a further embodiment, a plasma display panel includes a first substrate and a second substrate opposing one another with a predetermined gap therebetween. Address electrodes are formed on the second substrate. Barrier ribs are mounted in the gap between the first substrate and the second substrate to define a plurality of discharge cells. Phosphor layers formed in each of the discharge cells. Discharge sustain electrodes are formed in a direction intersecting the address electrodes such that each of the discharge cells is in communication with a pair of the discharge sustain electrodes, each of the discharge sustain electrodes including a discharge sustain electrode extension section that extends into the discharge cell such that a pair of opposing discharge sustain electrode extension sections is formed in each of the discharge cells, a distal end of each discharge sustain electrode extension section having an enlarged discharge sustain electrode extension section with an enlarged section width being larger than a width of the discharge sustain electrode extension section distal from a communicating pair of discharge sustain electrodes of the discharge cell. Among each pair of discharge sustain electrodes corresponding to a discharge cell, one of each pair is a scanning electrode that effects address discharge between address electrodes in a scan interval and an other of each pair is common electrode that effects display discharge between the common electrode and corresponding scanning electrode during a discharge sustain interval. Each of the address electrodes have an enlarged address electrode section at areas corresponding to the enlarged discharge sustain electrode extension section of an opposing scanning electrodes. 
     In a still further embodiment, plasma display panel screen brightness during sustain discharge of a plasma display panel is enhanced. The plasma display panel has a first substrate and a second substrate opposing one another with a predetermined gap therebetween. Address electrodes are formed on the second substrate. Barrier ribs are mounted in the predetermined gap between the first substrate and the second substrate to define a plurality of discharge cells. The discharge cells have a discharge cell gas excited by an initiator discharge voltage. Phosphor layers are formed in each of the discharge cells. Discharge sustain electrodes are formed in a direction intersecting the address electrodes such that each of the discharge cells is in communication with a pair of the discharge sustain electrodes. Each of the discharge sustain electrodes include a discharge sustain electrode extension section that extends into the discharge cell such that a pair of opposing discharge sustain electrode extension sections is formed in each of the discharge cells with a gap between distal ends of the opposing discharge electrode extension sections. The initiator discharge voltage is established as a function of the size of the gap and an amount of Xenon gas content of the discharge cell gas. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partial plan view of a plasma display panel according to a first embodiment of the present invention. 
         FIG. 2  is an enlarged plan view of a portion of a transparent electrode used in the plasma display panel of  FIG. 1 . 
         FIG. 3  is a partial plan view of a plasma display panel according to a second embodiment of the present invention. 
         FIG. 4  is a partial plan view of a plasma display panel according to a third embodiment of the present invention. 
         FIG. 5  is a partial cutaway perspective view of a conventional plasma display panel. 
         FIG. 6  is a partial plan view of the plasma display panel of  FIG. 5 . 
         FIG. 7  is a partial plan view of a conventional plasma display panel employing a T-shape discharge electrode configuration. 
         FIG. 8  is a partial plan view of a plasma display panel according to a fourth embodiment of the present invention. 
         FIG. 9  is a graph showing variations in the discharge initiation voltage as a function of discharge gaps and the amount of Xenon gas in the discharge gas. 
     
    
    
     DETAILED DESCRIPTION 
     Referring first to  FIG. 1 , in the plasma display panel (PDP) according to the first embodiment of the present invention, a plurality of address electrodes  21  is formed on a second substrate (not shown) along one direction (direction Y) of the same, and a plurality of discharge sustain electrodes  14  is formed on a first substrate (not shown) along a direction (direction X) substantially perpendicular to address electrodes  21 . 
     A plurality of barrier ribs  15  is formed in a space between the second substrate and the first substrate. One the barrier ribs  15  is formed between each adjacent pair of address electrodes  21  and is uniformly aligned with the same in the same manner as shown in  FIG. 5 . Barrier ribs  15  define discharge cells  23 R,  23 G, and  23 B, which are needed for plasma discharge. In the first embodiment, although barrier ribs  15  are described as being formed in a stripe pattern, the present invention is not limited to such a configuration. For example, it is possible in the present invention to use a closed barrier rib structure including barrier rib members that are aligned with address electrodes  21  and barrier rib members that intersect address electrodes  21  to thereby define discharge cells  23 R,  23 G, and  23 B. 
     Discharge sustain electrodes  14  include extension electrodes  12  and bus electrodes  13 . Extension electrodes  12  act to effect plasma discharge within discharge cells  23 R,  23 G, and  23 B, and are preferably realized using transparent ITO (Indium Tin Oxide) in order to ensure brightness levels. Bus electrodes  13  compensate for the high resistance of extension electrodes  12  (i.e., the high resistance of ITO) to enhance electric conductivity. Bus electrodes  13  are therefore preferably made of a metal material. 
     Bus electrodes  13  are formed substantially in parallel along direction Y (i.e., in a line pattern) and in such a manner that for each of discharge cells  23 R,  23 G, and  23 B, two of bus electrodes  13  are provided at substantially opposite ends thereof. A plurality of extension electrodes  12  is protruded from each of bus electrodes  13  and at areas within discharge cells  23 R,  23 G, and  23 B. As a result, for each of discharge cells  23 R,  23 G, and  23 B, an opposing pair of extension electrodes  12  is positioned therein. Extension electrodes  12  are formed also such that distal ends of opposing pairs within discharge cells  23 R,  23 G, and  23 B are provided at a predetermined distance. 
     With reference to  FIG. 2 , a distal end of each of extension electrodes  12  is formed including concave section A at a center of the distal end, and convex sections B formed extending from opposite sides of concave section A. Therefore, for each pair of opposing extension electrodes  12  within each of discharge cells  23 R,  23 G, and  23 B, long gap L, as seen in  FIG. 1 , is formed between opposing concave sections A, and relatively short gap S is formed between each of opposing convex sections B. This configuration results in the main discharge occurring initially where short gaps S are formed, after which discharge spreads to long gap L then to the remainder of discharge cells  23 R,  23 G, and  23 B. 
     Concave sections A of extension electrodes  12  act to concentrate discharge at centers of discharge cells  23 R,  23 G, and  23 B to thereby effect stable discharge. Convex sections B reduce the distance between distal ends of opposing extension electrodes  12  (over the prior art) so that the voltage needed for discharge is minimized. This advantage is realized by convex sections B while not significantly reducing the aperture ratio. 
     In an exemplary embodiment concave sections A and convex sections B of extension electrodes  12  are provided in a curved configuration, that is, lacking sharp angles. This is realized by the formation of connecting sections C between concave sections A and convex sections B, as seen in  FIG. 2 . In particular, for each of extension electrodes  12 , connecting sections C between concave section A and convex sections B are formed with a reducing slope as concave section A is approached. Using the natural spread of discharge, connecting sections C act to induce the discharge toward the long gaps from where it is started in the short gaps. 
     In more detail, there is a non-linear relation between discharge and the externally applied voltage. For example, if a discharge initialization voltage is 200V, discharge does not occur until 200V is reached and will not occur if a lesser voltage of, say, 199V is reached. However, discharge characteristics are such that once discharge occurs and is repeated (i.e., diffused), discharge is spread to peripheries by geometric progression. The main discharge is induced into the long gaps through such spreading. 
     The formation of concave sections A and convex sections. B of extension electrodes  12  is such that for each pair of bus electrodes  13  provided for each row of discharge cells  23 R,  23 G, and  23 B along direction Y, concave sections A and convex sections B may be formed at the distal ends of extension electrodes  12  corresponding to one of bus electrodes  13  or to both of bus electrodes  13  as described above. 
     Further, in the first embodiment, extension electrodes  12  of discharge sustain electrodes  14  are formed such that a distance to adjacent barrier ribs  15  is initially decreased in a direction toward proximal ends of extension electrodes  12 . Stated differently, the formation of extension electrodes  12  outside concave regions A and convex regions B is such that as a distance from the center of discharge cells  23 R,  23 G, and  23 B is increased, the distance between extension electrodes  12  and adjacent barrier ribs  15  in the direction bus electrodes  13  are formed (direction Y) is initially decreased. This is continued for a predetermined length of extension electrodes  12  along the direction barrier ribs  15  are formed (direction X), after which a predetermined width of extension electrodes  12  is maintained for the remainder of its length, such that the distance to adjacent barrier ribs  15  is increased. Since the proximal ends of extension electrodes  12  contribute little to the generation of discharge, such a configuration improves discharge efficiency. Also, a high aperture ratio is ensured by having the proximal ends formed to a smaller width than the distal ends. 
     Black stripe  17  may be formed between each of non-paired adjacent discharge sustain electrodes  14  to improve contrast. 
     Referring now to  FIG. 3 , a partial plan view of a plasma display panel according to a second embodiment of the present invention is shown. 
     The PDP of the second embodiment has the same basic structure as that of the first embodiment, and only extension electrodes  32  of discharge sustain electrodes  34  are formed differently. In particular, while furthermost parts of distal ends of extension electrodes  32  are formed as in the first embodiment, a width of extension electrodes  32  in a direction bus electrodes  33  are formed is maintained throughout a length of extension electrodes  32  in the direction barrier ribs  15  are formed. 
     Referring to  FIG. 4 , a partial plan view of a plasma display panel according to a third embodiment of the present invention is shown. 
     The PDP of the third embodiment has the same basic structure as that of the first embodiment, and only extension electrodes  42  of discharge sustain electrodes  44  are formed differently. In particular, centers of distal ends of extension electrodes  42  include only concave sections and no convex sections are formed as in the first embodiment. Also, starting from the distal ends of extension electrodes  42  and in a direction toward proximal ends of the same, outer long edges of extension electrodes  42  are formed with a straight section of a predetermined width in a direction bus electrodes  43  are formed. This is continued for a predetermined length of extension electrodes  42 , then the long edges are slanted inwardly to decrease the width of extension electrodes  42  until reaching approximately the point at which extension electrodes  42  are connected to bus electrodes  43 . At this point, the long edges of extension electrodes  42  are straightened to be substantially parallel to barrier ribs  15 , and this configuration is continued for the remainder of extension electrodes  42 . 
     In the PDP of the present invention described above, the formation of the discharge sustain electrodes is optimized to minimize unneeded areas of the electrodes, thereby resulting in limiting the discharge current and improving discharge efficiency. 
     Further, the aperture ratio is increased by minimizing the size of the discharge sustain electrodes, which have 95% transmissivity. That is, even with the reduction in the area of the discharge sustain electrodes, a brightness level that is identical to or higher than the prior art is realized. This allows for an improvement in the aperture ratio and a reduction in the amount of material used to form the discharge sustain electrodes. 
     With reference to  FIG. 8 , showing a fourth embodiment of the present invention, among a pair of discharge sustain electrodes  116  and  118  corresponding to each of discharge cells  23 R,  23 G, and  23 B, one is scanning electrode  116  that effects address discharge between address electrodes in a scan interval, and the other is common electrode  118  that effects display discharge between itself and corresponding scanning electrode  116  during a discharge sustain interval. 
     Address electrodes  108  have enlarged section  108   b  corresponding to the formation of protrusion  116   b  of scanning electrodes  116  and at areas opposing scanning electrodes  116 . This allows scanning electrodes  116  to be formed having an increased area. 
     That is, each of address electrodes  108  includes linear section  108   a  that extends along a longitudinal direction (direction Y), and enlarged sections  108   b  that are expanded in a direction of the width of the PDP (direction X). Enlarged sections  108   b  are expanded corresponding roughly to a shape of protrusions  116   b  of scanning electrodes  116 . 
     In more detail, a portion of each of enlarged sections  108   b  of address electrodes  108  corresponding to a distal end portion of each of protrusions  116   b  of scanning electrodes  116  is substantially quadrilateral, having width W 1 . Further, a portion of each of enlarged sections  108   b  of address electrodes  108  corresponding to a proximal end portion of each of protrusions  116   b  of scanning electrodes  116  has width W 2  that decreases as corresponding bus electrode  116   a  of scanning electrode  116  is approached. For reference, width W 3  of linear portion  108   a  of one of address electrodes  108  is shown. In this exemplary embodiment, the following inequalities are satisfied: W 1 &gt;W 2 &gt;W 3 . 
     With the formation of enlarged sections  108   b  of address electrodes  108  at areas corresponding to the formation of scanning electrodes  116  as described above, address discharge between address electrodes  108  and scanning electrodes  116  may be enhanced, and interference of common electrodes  118  during address discharge may be reduced. Therefore, address discharge is stabilized and mis-discharge is prevented. 
     Referring back to  FIG. 1  as a representative embodiment, discharge sustain electrodes have a pair of opposing long gaps L and short gaps S such that a discharge initiation voltage Vf is reduced. Therefore, the amount of Xenon (Xe) gas contained in the discharge gas may be increased with an increase in the discharge initiation voltage Vf. 
     In an exemplary embodiment, the discharge gas contains 10% or more, preferably between 10 and 60%, of Xe. A stronger emission of ultraviolet rays is possible during sustain discharge as a result of the increased amount of Xe such that screen brightness is enhanced. 
     The relation between the amount of Xe contained in the discharge gas and the discharge gap between opposing protrusions is explained with reference to Table 1 and  FIG. 9 . Among the different discharge gaps, the long gaps are referred to as first discharge gaps G 1 , and the short gaps are referred to as second discharge gaps G 2 . 
     If A is the sum of the size of first discharge gaps G 1  and the size of second discharge gaps G 2 , Table 1 shows the A values obtained through experimentation, that is, the A values in which driving is possible by a suitable discharge initiation voltage Vf according to variations in the amount of Xe in discharge gas. Suitable PDP driving was not possible when the discharge gas contained 60% or more of Xe. 
     In table 1, F(A+Xe) shows the addition of the A values (with units of micrometers ignored) with the amount of Xe in the discharge gas (with the percentage of this amount ignored). Further, the discharge efficiencies, which are measured according to the amount of Xe in the discharge gas, are relative values based on a value of 1 for a 5% amount of Xe in discharge gas. 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Xe amount 
                 Suitable A values 
                   
                   
               
               
                   
                 in discharge 
                 according to Xe 
                   
                 Discharge 
               
               
                   
                 gas (%) 
                 amount (μm) 
                 F(A + Xe) 
                 efficiency 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 5 
                 180–210 
                 185–215 
                 1 
               
               
                   
                 7 
                 170–210 
                 177–217 
                 1.05 
               
               
                   
                 10 
                 165–210 
                 175–220 
                 1.35 
               
               
                   
                 15 
                 155–195 
                 170–210 
                 1.45 
               
               
                   
                 20 
                 147–190 
                 167–210 
                 1.57 
               
               
                   
                 25 
                 143–187 
                 168–213 
                 1.76 
               
               
                   
                 30 
                 137–187 
                 167–217 
                 2.0 
               
               
                   
                 35 
                 135–185 
                 170–220 
                 2.26 
               
               
                   
                 40 
                 133–185 
                 173–225 
                 2.41 
               
               
                   
                 50 
                 125–180 
                 175–230 
                 2.89 
               
               
                   
                 55 
                 120–177 
                 175–232 
                 3.12 
               
               
                   
                 60 
                 110–170 
                 170–240 
                 3.48 
               
               
                   
                   
               
             
          
         
       
     
     It is evident from Table 1 that by increasing the amount of Xe in discharge gas from 5% to 60%, when the size of first and second discharge gaps G 1  and G 2  are made small, driving at a suitable discharge initiation voltage Vf is possible and discharge efficiency is improved. In particular, compared to when the amount of Xe in discharge gas is 5%, discharge efficiency significantly improved when the amount of Xe is 10% or more. Accordingly, in the PDP of this exemplary embodiment, in addition to the above formation of the protrusions of the discharge sustain electrodes, an amount of 10% or more (to a maximum of 60%) of Xe is contained in discharge gas to thereby improve discharge efficiency. 
       FIG. 9  is a graph showing variations in the discharge initiation voltage Vf as a function of F(A+Xe). 
     With reference to  FIG. 9 , driving is performed in a range of 180 to 210V, which is considered a suitable discharge initiation voltage Vf in the PDP industry, when the F(A+Xe) value is in the range of 167 to 240 and while the amount of Xe in the discharge gas is between 10 and 60%. Accordingly, the PDP according to this exemplary embodiment realizes a discharge sustain electrode configuration that includes 10 to 60% Xe in the discharge gas and a value of F(A+Xe) between 167 and 240. 
     Although embodiments of the present invention have been described in detail hereinabove, it should be clearly understood that many variations and/or modifications of the basic inventive concepts herein taught which may appear to those skilled in the present art will still fall within the spirit and scope of the present invention, as defined in the appended claims.