Patent Publication Number: US-7714510-B2

Title: Plasma display apparatus

Description:
This application claims the benefit of Korean Patent Application No. 10-2006-0048816 filed on May 30, 2006, which is hereby incorporated by reference for all purposes as if fully set forth herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates, in general, to a plasma display apparatus and, more particularly, to a panel equipped in a plasma display apparatus. 
     2. Description of the Related Art 
     As to the plasma display panel, the barrier rib formed between the front substrate and the rear substrate forms one unit cell. Inside of each cell, a main discharge gas such as Ne, He, or Ne+He mixed gas and an inactive gas containing a small amount of xenon is filled. When a discharge is generated by a high frequency voltage, the inactive gas generates the Vacuum Ultraviolet rays, and stimulates the phosphor formed between the barrier ribs to display an image. Such plasma display panel can be implemented with a thin and light configuration, therefore, it is highlighted as future display device. 
       FIG. 1  is a drawing showing the structure of a plasma display panel of the related art. Referring to  FIG. 1 , as to a plasma display apparatus, a front panel  100  and a rear panel  110  is disposed in parallel with a constant distance. On the front panel  100 , a plurality of sustain electrode pairs are disposed on a front substrate  101  where an image is displayed, when the sustain electrode pair is comprised of a scan electrode  102  and a sustain electrode  103 . On the rear panel  100  which is a backside, a plurality of address electrodes intersecting with the plurality of sustain electrode pairs are disposed on a rear substrate  111 . 
     The front panel  100  is comprises of a scan electrode  102  including a transparent electrode  102   a ,  103   a  and a bus electrode  102   b ,  103   b , and a sustain electrode  103  while the scan electrode  102  and the sustain electrode  103  form a pair and a transparent electrode  102   a ,  103   a  is made of a transparent Indium Tin Oxide ITO. The scan electrode  102  and the sustain electrode  103  are covered with a front dielectric layer  104 . The protective layer  105  is formed on the front dielectric layer  104 . 
     The rear panel  110  includes a barrier rib  112  for partitioning off a discharge cell. A plurality of address electrodes  113  are arranged in parallel with the barrier rib  112 . On the address electrode  113 , Red R, Green G, and Blue B phosphors  114  are coated. A rear dielectric layer  115  is formed between the address electrode  113  and the phosphors  114 . 
     In the meantime, the transparent electrodes  102   a ,  103   a  comprising the scan electrode  102  or the sustain electrode  103  is made of ITO which is expensive. Transparent electrode  102   a ,  103   a  causes the raising of the manufacturing cost of the plasma display panel. Therefore, manufacturing the plasma display panel which can obtain the sufficient color matching function and the driving characteristic for a user while decreasing the manufacturing cost is requested in recent days. 
     SUMMARY 
     Accordingly, the present invention has been made in view of the above problems occurring in the prior art, and it is an object of the present invention to provide a plasma display apparatus capable of improving the flickering of the display image and the spot generation, reducing the manufacturing cost by eliminating the transparent electrode made of ITO. 
     To achieve the above object, according to an aspect of the present invention, there is provided a plasma display apparatus, including a front substrate; a plurality of first, second electrodes formed on the front substrate; a rear substrate that is faced with the front substrate; a plurality of third electrodes formed on the rear substrate; and a discharge cell that is disposed in the place where the first, the second electrode intersect with the third electrode, wherein at least one of the plurality of the first and the second electrode is formed with one layer, wherein the thickness of at least one of the plurality of the first and the second electrode ranges from 3 μm to 7 μm. 
     According to an aspect of the present invention, at least one of the plurality of the first, the second electrode comprises: a line portion formed in the direction intersecting with the third electrode; and a protrusion protruded from the line portion. 
     The resistance of at least one of the plurality of the first and the second electrode ranges from 50Ω to 65Ω. 
     The resistance of at least one of the plurality of the first and the second electrode ranges from 40Ω to 90Ω. 
     The resistance of the electrode is a resistance between the both ends of the electrode positioned in an effective display region of the panel. 
     The line portion is two or more, and the gap between the adjacent line portion among the two or more line portions ranges 80 μm to 120 μm. 
     The protrusion forms at least one closed loop. 
     The plasma display apparatus according to an aspect of the present invention further comprises a front dielectric layer covering the first, the second electrode, wherein at least one of the first and the second electrode is darker than the front dielectric layer. 
     On the rear substrate, a dielectric layer; a barrier rib partitioning off the discharge cell; and a phosphor layer is formed. 
     A plasma display apparatus according to another aspect of the present invention comprises a front substrate; a plurality of first, second electrodes formed on the front substrate; a rear substrate that is faced with the front substrate; a plurality of third electrodes formed on the rear substrate; a line portion formed in the direction intersecting with the third electrode; and a protrusion protruded from the line portion, wherein at least one of the plurality of the first and the second electrodes is formed with one layer, wherein the width of the protrusion ranges from 35 μm to 70 μm. 
     The width of the protrusion ranges from 35 μm to 45 μm. 
     The protrusion is two or more. 
     The plasma display apparatus of claim  10 , wherein the protrusion forms at least one closed loop. 
     A plasma display apparatus according to further aspect of the present invention comprises a front substrate; a plurality of first, second electrodes formed on the front substrate; a rear substrate that is faced with the front substrate; a plurality of third electrodes formed on the rear substrate; a line portion formed in the direction intersecting with the third electrode; and a protrusion protruded from the line portion, wherein at least one of the plurality of the first and the second electrodes is formed with one layer, wherein the gap between the protrusion of the first electrode and the protrusion of the second electrode ranges from 15 μm to 165 μm. 
     The gap between the protrusion of the first electrode and the protrusion of the second electrode ranges from 60 μm to 120 μm. 
     A plasma display apparatus according to further aspect of the present invention further comprises a front dielectric layer covering the first, the second electrode, wherein at least one of the first and the second electrode is darker than the front dielectric layer. 
     The protrusion forms at least one closed loop. 
     A plasma display apparatus according to further aspect of the present invention comprises: a front substrate; a plurality of first, second electrodes formed on the front substrate; a rear substrate that is faced with the front substrate; a plurality of third electrodes formed on the rear substrate; a line portion formed in the direction intersecting with the third electrode; and a protrusion protruded in the direction of barrier rib which is adjacent to the line portion from the line portion, wherein at least one of the plurality of the first and the second electrodes is formed with one layer, wherein the length of the protrusion ranges from 30 μm to 100 μm. 
     The length of the protrusion ranges from 50 μm to 100 μm. 
     The gap between the adjacent barrier ribs ranges from 70 μm or less. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be described in detail with reference to the following drawings in which like numerals refer to like elements. The accompany drawings, which are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention and together with the description serve to explain the principles of the present invention. In the drawings: 
         FIG. 1  is a drawing showing the structure of a plasma display panel equipped in the plasma display apparatus of the related art. 
         FIG. 2   a  is a drawing showing a first embodiment of a plasma display panel according to the present invention. 
         FIG. 2   b  is a drawing showing an embodiment of the electrode arrangement of a plasma display panel 
         FIG. 3  is a drawing showing a first embodiment of the electrode structure of a plasma display panel according to the present invention. 
         FIG. 4  is a drawing showing a second embodiment of a plasma display panel according to the present invention. 
         FIG. 5   a  to  FIG. 5   b  is a drawing showing a second embodiment of the electrode structure of a plasma display panel according to the present invention. 
         FIG. 6  is a drawing showing a third embodiment of the electrode structure of a plasma display panel according to the present invention. 
         FIG. 7  is a drawing showing a fourth embodiment of the electrode structure of a plasma display panel according to the present invention. 
         FIG. 8  is a drawing showing a fifth embodiment of the electrode structure of a plasma display panel according to the present invention. 
         FIG. 9  is a drawing showing a sixth embodiment of the electrode structure of a plasma display panel according to the present invention. 
         FIG. 10  is a drawing showing a seventh embodiment of the electrode structure of a plasma display panel according to the present invention. 
         FIG. 11  is a drawing showing a eighth embodiment of the electrode structure of a plasma display panel according to the present invention. 
         FIG. 12  is a drawing showing a ninth embodiment of the electrode structure of a plasma display panel according to the present invention. 
         FIG. 13  is a drawing showing a tenth embodiment of the electrode structure of a plasma display panel according to the present invention. 
         FIG. 14   a  to  FIG. 14   b  is a drawing showing an eleventh embodiment of the electrode structure of a plasma display panel according to the present invention. 
         FIG. 15  is a drawing showing an embodiment of the method in which a frame is time-divided into a plurality of subfields for driving a plasma display panel. 
         FIG. 16  is a waveform diagram showing an embodiment of driving signals for driving a plasma display panel. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Preferred embodiments of the present invention will be described in a more detailed manner with reference to the drawings. 
     Hereinafter,  FIG. 2   a  is a drawing showing a first embodiment of a plasma display panel according to the present invention. 
     Referring to  FIG. 2   a , the plasma display panel includes a front panel  200  and a rear panel  210  coalesced with a predetermined gap. 
     The plasma display panel includes an address electrode  213 , and barrier ribs. The address electrode  213  is formed on the rear substrate  211  in the direction intersecting with the sustain electrode pair  202 ,  203 , while barrier rib  212   a ,  212   b  partitions off a plurality of discharge cells. 
     The front panel  200  includes a sustain electrode pair  202 ,  203  which is formed on a front substrate  201  with forming a pair. According to a function, the sustain electrode pair  202 ,  203  are classified into a scan electrode  202  and a sustain electrode  203 . The sustain electrode pair  202 ,  203  is covered with a front dielectric layer  204  that limits the discharge current and insulates between the electrode pair. A passivation layer  205  is formed on the top of the front dielectric layer  204 , thereby, the front dielectric layer  204  is protected from the sputtering of the charged particles generated during the gaseous discharge and the emission efficiency of the secondary electron can be enhanced. 
     On the rear panel  210 , a barrier rib  212  partitioning off a plurality of discharge spaces, that is, a discharge cell is formed on the lower substrate  211 . Further, an address electrode  213  is arranged in the direction intersecting with sustain electrode pair  202 ,  203 . A phosphor  214  which is light-emitted by the ultraviolet ray generated during the gaseous discharge time to generate a visible light is coated onto the surface of the barrier rib  212  and the rear dielectric layer  215 . 
     In this way, the inactive gas containing a main gas including Ne, He, or the mixed gas Ne+He, and a small amount of xenon are filled in the discharge cell surrounded by the barrier rib  212   a ,  212   b.    
     The pressure of the gas in the panel may range from 350 Torr to 500 Torr so as to enhance the discharge efficiency and to facilitate the panel manufacturing processing. 
     At this time, the barrier rib  212  is comprised of a column barrier rib  212   a  developed into the direction in parallel with the address electrode  213 , and a row barrier rib  212   b  developed into the direction intersecting with the address electrode  213 , which divides the discharge cell physically and prevents the ultraviolet ray generated by a discharge and the visible light from being leaked out into the adjacent discharge cell. 
     Further, in the plasma display panel according to an embodiment of the present invention, the sustain electrode pair  202 ,  203  is made of an opaque metal electrode differently from the sustain electrode pair  102 ,  103  shown in  FIG. 1 . That is, ITO which is a conventional transparent electrode material is not used, while the sustain electrode pair  202 ,  203  is formed by using the conventional material of the bus electrode such as Ag, Cu or Cr. That is, each sustain electrode pair  202 ,  203  of the plasma display panel according to the embodiment of the present invention does not include the conventional ITO electrode. The sustain electrode pair  202 ,  203  of the plasma display panel according to the embodiment of the present invention is made of one layer with the sole bus electrode. 
     For example, it is preferable that the sustain electrode pair  202 ,  203  according to the embodiment of the present invention is made of silver. It is preferable that the silver Ag has the photosensitivity property. Further, it is preferable that the sustain electrode pair  202 ,  203  according to the embodiment of the present invention is more gloomy and the permeability of the light is more low than the front dielectric layer  204  formed on the front substrate  201 . 
     It is preferable that the thickness of the electrode lines  202   a    202   b ,  203   a ,  203   b  range from 3 μm to 7 μm. In case the electrode lines  202   a    202   b ,  203   a ,  203   b  are formed with a range of such thickness, with obtaining a range of resistance with which the plasma display panel can normally operate and a necessary aperture ratio, the light reflected to the front of the plasma display apparatus can be prevented from the reduction of luminance of an image resulting from the blocking of the electrode. 
     It is preferable that the resistance of the electrode lines  202   a ,  202   b ,  203   a ,  203   b  ranges from 50Ω to 65Ω, with the thickness as described in the above. Further, it is preferable that the resistance of electrode lines  202   a ,  202   b ,  203   a ,  203   b  ranges from 90Ω to 40 in order that the capacitance of the panel is not increased for obtaining the drive margin of the panel. 
     It is preferable that the resistance of electrode lines  202   a ,  202   b ,  203   a ,  203   b  is the resistance between the both ends of the electrode adjacent to the pad portion (not shown) connecting the driver circuit (not shown) of the panel to the electrode lines  202   a ,  202   b ,  203   a ,  203   b , or it can be the resistance of the both ends between the electrodes positioned in the effective display region of the panel. 
     The thickness, or the width of each R, G, B phosphor layer  214  can be substantially identical or can be different. In case the thickness of each R, G, B phosphor layer  214  is different each other, the thickness of the phosphor layer  214  in G discharge cell or B discharge cell can be bigger than the thickness of the phosphor layer  214  in R discharge cell. 
     As shown in  FIG. 2   a , it is preferable that the sustain electrodes  202 ,  203  is formed in one discharge cell with a plurality of electrode lines. That is, it is preferable that the first sustain electrode  202  is formed with two electrode lines  202   a ,  202   b , while the second sustain electrode  203  is arranged to be symmetrized with the first sustain electrode  202  based on the center of the discharge cell, and formed with two electrode lines  203   a ,  203   b . It is preferable that the first, and the second sustain electrodes  202 ,  203  are the scan electrode and the sustain electrode respectively. 
     In that case, the aperture ratio and the discharge diffusion efficiency are considered according to the use of an opaque sustain electrode pair  202 ,  203 . That is, the electrode line having the narrow width is used in consideration of the aperture ratio, while a plurality of electrode lines are used in consideration of the discharge diffusion efficiency. At this time, it is preferable that the number of electrode lines is determined in consideration of the aperture ratio and the discharge diffusion efficiency and discharge diffusion efficiency at the same time. 
     In the meantime, though not shown in  FIG. 2   a , each electrode lines  202   a ,  202   b ,  203   a ,  203   b  of does not directly contact the front substrate  201 , but can be formed on a predetermined black layer. That is, the black layer is formed between the front substrate  201  and each electrode lines  202   a ,  202   b ,  203   a ,  203   b , the metachromatism of the front substrate  201  which can be generated when the front substrate  201  and each electrode lines  202   a ,  202   b ,  203   a ,  203   b  directly contact can be improved. 
     The structure of the panel shown in  FIG. 2   a  is just an embodiment of the structure of a plasma display panel according to the present invention. Therefore, the present invention is not restricted to the structure of the plasma display panel shown in  FIG. 2 . For example, a Black Matrix BM that blocks a light to reduce a reflection by absorbing the external light generated in the outside and to improve the purity and the contrast of the front substrate  201  can be formed on the front substrate  201 , while the black matrix is available with both an unitary type and a separation type. 
     In the meantime, the black matrix can be formed with the black layer simultaneously in the forming process to be physically connected, while they are not physically connected when they are formed in different time point. Further, in case of being physically connected to be formed, the black matrix and the black layer are formed with the same material. However, in case the black matrix and the black layer are separated physically to be formed, they can be made of other material. 
     Further, the panel structure shown in  FIG. 2  shows a close type in which the discharge cell has a closed architecture due to the column barrier rib  212   a  and a row barrier rib  212   b . However, it is not restricted to such type, but a stripe type that has only the row barrier rib  212   b  or a fish bone structure where a protrusion is formed with a predetermined gap on the column barrier rib  212   a  can be used. 
     In addition, as to the plasma display panel according to an embodiment of the present invention, various barrier rib structures having various shapes as well as the barrier rib structure shown in  FIG. 2  is available. 
     A differential type barrier rib structure where the height of the column barrier rib  212   a  and the row barrier rib  212   b  are different, a channel type barrier rib structure where a channel which can be used as ventilating passage is formed in at least one of the column barrier rib  212   a  and the row barrier rib  212   b , and a hollow type barrier rib structure where a hollow is formed in at least one of the column barrier rib  212   a  and the row barrier rib  212   b  can be used. 
     Here, in the differential barrier rib structure, it is preferable that the height of the row barrier rib  212   b  is higher than the height of the column barrier rib  212   a . In the channel type barrier rib structure or the hollow type barrier rib structure, it is preferable that a channel or a hollow is formed in the row barrier rib  212   b.    
     In the meantime, in the embodiment of the present invention, it is illustrated that the discharge cell R, G and B is arranged in the same line. However, the other shape can be arranged. For example, the arrangement of a delta type where the discharge cell R, G and B is arranged in a triangle form can be used. In addition, the various polygonal shape including a pentagon, a hexagon as well as the square shape can be used for the shape of the discharge cell. 
     Further, the width of the column barrier rib  212   a  and the width of the row barrier rib  212   b  can be different. The width of the barrier rib can be the width of the upper part or the lower part. In addition, it is preferable that the width of the row barrier rib  212   b  ranges from 1.0 times to 5.0 times of the width of the column barrier rib  212   a.    
     In the meantime, the pitch of R, G, B discharge cell of the plasma display panel according to the embodiment of the present invention can be substantially identical. However, the pitch of R, G, B discharge cell can be different so as to fit the color temperature in R, G, B discharge cell. In this case, the pitch of R, G, B discharge cell can be different discharge cell-by-cell. However, only the pitch of the discharge cell which expresses one color of R, G, B discharge cell can be different. For example, the pitch of R discharge cell is most small, and the pitch of G, B discharge cell can be bigger than the pitch of R discharge cell. 
     Further, as to the address electrode formed in the rear substrate  211 , the width or the thickness can be substantially uniform. However, the width or the thickness of the inside of the discharge cell can be different from the width or the thickness of the outside of the discharge cell. For example, the width or the thickness of the inside of the discharge cell can be broader or thicker than the width or the thickness of the outside of the discharge cell. 
     It is preferable that the material of the barrier rib  212   a ,  212   b  is not used with a lead Pb, or with a little bit lead such as 0.1 wt % of total weight or 1000 Parts Per Million PPM or less. 
     Here, in the case that the whole content of the lead is 1000 PPM or less, the content of the lead is 1000 PPM or less on the basis of the weight of plasma display panel. 
     On the other hand, the content of the lead in a specific component of the plasma display panel can be 1000 PPM or less. For example, the lead of the barrier rib, the content of the lead in the electrode or the lead of the dielectric layer can be 1000 PPM or on the basis of the weight of each component such as the barrier rib, the dielectric layer, and the electrode. 
     Furthermore, the content of the lead of all the compositional elements such as the barrier rib, the dielectric layer, the electrode and the phosphor layer can be 1000 PPM or less on the basis of the weight of the plasma display panel. In this way, the reason of setting the whole content of the lead with 1000 PPM or less is that the lead influences the bad effect on the human body. 
       FIG. 2   b  is a drawing showing an embodiment of the electrode arrangement of a plasma display panel. 
     As shown in  FIG. 2   b , it is preferable that a plurality of discharge cells forming a plasma display panel are arranged as a matrix type. The plurality of discharge cells are positioned in the intersection of the scan electrode lines Y 1  to Ym, the sustain electrode lines Z 1  to Zm and the address electrode lines X 1  to Xn. The scan electrode Y 1  to Ym is sequentially drived, while the sustain electrode Z 1  to Zm is commonly drived. The address electrode lines X 1  to Xn is divided into even number lines and odd number lines to be drived. 
     The electrode arrangement shown in  FIG. 2   b  is just an embodiment of the electrode arrangement of the plasma display panel according to the present invention. Therefore, the present invention is not restricted to the electrode arrangement of the plasma display panel and the driving method shown in  FIG. 2   b.    
     For example, the dual scan mode or the double scan mode in which two scan electrode lines in the scan electrode lines Y 1  to Ym are drived simultaneously can be available. Here, the dual scan method is a mode in which the plasma display panel is divided into two regions with an upper region and a lower region, while one scan electrode line which belongs to the upper region and the lower region respectively is drived simultaneously. On the other hand, the double scan mode is a mode in which two scan electrode lines which are sequentially arranged are drived simultaneously. 
     The first embodiment of the plasma display panel structure according to the present invention shown in  FIG. 22  will be described in detail with  FIG. 3 . 
       FIG. 3  is a cross-sectional view showing a first embodiment of the electrode structure of a plasma display panel according to the present invention, in which only the arrangement structure of the sustain electrode pair  202 ,  203  formed in a discharge cell in the plasma display panel shown in  FIG. 2   a  is briefly shown. 
     As shown in  FIG. 3 , the sustain electrodes  202 ,  203  according to a first embodiment of the present invention are formed as a pair to be symmetrical on the substrate based on the center of the discharge cell. Each sustain electrode is comprised of a line portion including at least two electrode lines  202   a ,  202   b ,  203   a ,  203   b  crossing the discharge cell, and a protrusion including at least one projecting electrode  202   c ,  203   c  which is protruded to the center of the discharge cell in the discharge cell and connected to the electrode line  202   a ,  203   a  which is the closest to the center of the discharge cell. Further, it is preferable that, as shown in  FIG. 4 , each sustain electrode  202 ,  203  further includes one bridge electrode  202   d ,  203   d  connecting the two electrode lines  202   a  and  202   b ,  203   a  and  203   b.    
     The electrode lines  202   a ,  202   b ,  203   a ,  203   b  cross the discharge cell, and extending to the direction of the plasma display panel. The electrode line according to the first embodiment of the present invention narrowly forms a width so as to improve the aperture ratio. Further, it is preferable that a plurality of electrode lines  202   a ,  202   b ,  203   a ,  203   b  are used so as to improve the discharge diffusion efficiency while the number of electrode lines are determined in consideration of the aperture ratio. 
     It is preferable that projecting electrodes  202   c ,  203   c  are connected to electrode lines  202   a ,  203   a  which are closest to the center of the discharge cell in one discharge cell, and protruding to the center of the discharge cell. Projecting electrodes  202   c ,  203   c  lower the firing voltage in driving the plasma display panel. 
     The first embodiment of the present invention includes projecting electrodes  202   c ,  203   c  connected to each electrode line  202   a ,  203   a  since the firing voltage increases due to the distance c of the electrode line  202   a ,  203   a . The firing voltage of the plasma display panel can be lowered, since a discharge can be generated in a low firing voltage between the projecting electrodes  202   c ,  203   c  which are formed closely. Here, the firing voltage is a voltage level where a discharge is initiated when a pulse is supplied to at least one electrode. 
     As to the projecting electrodes  202   c ,  203   c , the size is very small. Therefore, due to the tolerance of the manufacturing process, the width W 1  of the portion connected to electrode lines  202   a ,  203   a  of projecting electrodes  202   c ,  203   c  can be broader than the width W 2  of the end portion of the projecting electrode, while, if necessary, the width W 2  can be broader than the width W 1 . 
     It is preferable that the gap between two adjacent electrode lines that form a sustain electrode pair  203 ,  202  respectively, that is, the gap between  203   a  and  203   b  or the gap between  202   a  and  202   b , ranges from 80 μm to 120 μm. In case the gap between two adjacent electrode lines has such value, the aperture ratio of the plasma display panel can be obtained sufficiently, the luminance of the display image can be increased, and the discharge diffusion efficiency in a discharge space can be increased. 
     It is preferable that the width W 1  of projecting electrodes  202   c ,  203   c  ranges from 30 μm to 70 μm. In case the width W 1  of projecting electrodes  202   c ,  203   c  has such value, the light reflected to the front of the plasma display apparatus can be prevented from the reduction of luminance of an image resulting from the blocking of the electrode with a small aperture ratio of the plasma display panel. 
     Further, when the width W 1  of projecting electrodes  202   c ,  203   c  ranges from 35 μm to 45 μm, the luminance of the display image can be improved, and the discharge efficiency can be optimized. It is preferable that the gap a between the projecting electrodes  202   c ,  203   c  ranges from 15 μm to 165 μm. In case the gap a between the projecting electrodes  202   c ,  203   c  has such a value, the gap a, the proper firing voltage for the plasma display panel drive can be obtained. 
     In addition, in order to prevent the discharge between the projecting electrodes  202   c ,  203   c  from being generated over the critical value and shortening the lifetime of the electrode, the gap a between the projecting electrodes  202   c ,  203   c  can be 15 μm to 165 μm. 
     The bridge electrode  202   d ,  203   d  connects two electrode lines  202   a  and  202   b ,  203   a  and  203   b  which form the sustain electrode  202 ,  203  respectively. The bridge electrode  202   d ,  203   d  helps the discharge generated through projecting electrodes  202   c ,  203   c  to be easily diffused to the electrode lines  202   b ,  203   b  which are far from the center of the discharge cell. 
     As to the electrode structure according to the first embodiment of the present invention, the number of electrode lines can be suggested like that, thereby, the aperture ratio can be improved. Further, the firing voltage can be lowered by forming projecting electrodes  202   c ,  203   c . Further, the discharge diffusion efficiency is increased with electrode lines  202   b ,  203   b  and bridge electrodes  202   d ,  203   d  when electrode lines  202   b ,  203   b  are far from the center of the discharge cell. The luminous efficiency of the plasma display panel, as a whole, can be improved. That is, the brightness of the present invention is equal to the brightness of the conventional plasma display panel or brighter than the brightness of the conventional plasma display panel. Therefore, it is possible not to use an ITO transparent electrode. 
       FIG. 4  is a perspective drawing showing a second embodiment of a plasma display panel according to the present invention. 
     As shown in  FIG. 4 , the second embodiment of the plasma display panel according to the present invention includes a front panel  400  and a rear panel  410  which are coalesced each other with a predetermined gap, a barrier rib  412 . The address electrode  413  is formed in the rear panel  410  in the direction intersecting with a sustain electrode pair  402 ,  403 , while the barrier rib  412  partitions off a plurality of discharge cells. Here, the same description of the content described in the first embodiment among the features of the present invention of the plasma display panel according to the second embodiment of the present invention will be omitted. 
     It is preferable that the sustain electrode pair  402 ,  403  according to the second embodiment of the present invention are made of only an opaque metal electrode. Accordingly, the manufacturing cost of the plasma display panel can be lowered. That is, it is preferable that each sustain electrode pair  402 ,  403  of the plasma display panel according to the present invention does not include the conventional ITO electrode, but made of one layer with the sole bus electrode. 
     For example, it is preferable that each sustain electrode pair  402 ,  203  according to the embodiment of the present invention is made of silver. It is preferable that the silver has a photosensitivity characteristic. Further, as to the sustain electrode pair  402 ,  403  according to the embodiment of the present invention, it is preferable that the color of which is more dark than that of the front dielectric layer  404  formed in the front substrate  401 , and the permeability of the light is more low. 
       FIG. 4  shows the unit discharge cell R, G, B. Considering the aperture ratio and the discharge diffusion efficiency, the sustain electrode  402 ,  403  is formed in one discharge cell with a plurality of electrode lines. Further, in the second embodiment of the present invention, provided is the second projecting electrode  402   e ,  403   e  extended to the opposite direction of the center of the discharge cell, such that the discharge efficiency can be improved than the first embodiment of the present invention. 
     The structure illustrated in  FIG. 4  is just an embodiment of the structure of the plasma panel according to the present invention. Therefore, the present invention is not restricted to the plasma display panel structure illustrated in  FIG. 4 . 
     The detailed description on the structure of the sustain electrode pair  402 ,  403  according to the second embodiment of the present invention shown in  FIG. 4  will be described in  FIG. 5   a  to  FIG. 7 . 
       FIG. 5   a  is a cross-sectional view showing a second embodiment of the electrode structure of a plasma display panel according to the present invention, briefly showing only the layout structure of the sustain electrode pair  402 ,  403  formed in one discharge cell in the plasma display panel shown in  FIG. 4 . 
     As shown in  FIG. 5   a , each sustain electrode  402 ,  403  is comprised of at least two electrode lines  402   a ,  402   b ,  403   a ,  403   b  crossing the discharge cell, a first projecting electrode  402   c ,  403   c  which is protruded to the center of the discharge cell in the discharge cell and connected to the electrode line  402   a ,  403   a  which is the closest to the center of the discharge cell, a bridge electrode  402   d ,  403   d  connecting the two electrode lines  402   a  and  402   b ,  403   a  and  403   b , and a second projecting electrode  402   e ,  403   e  which is protruded to the opposite direction of the center of the discharge cell in the discharge cell and connected to the electrode line  402   b ,  403   b  which is most far from the center of the discharge cell. 
     The electrode lines  402   a ,  402   b ,  403   a ,  403   b  cross the discharge cell, and extending to the direction of the plasma display panel. It is preferable that the electrode line according to the second embodiment of the present invention narrowly forms a width so as to improve the aperture ratio. Preferably, the width of electrode line ranges from 20 μm to 70 μm to improve the aperture ratio and easily generate a discharge. 
     As shown in  FIG. 5   a , the electrode line  402   a ,  403   a  which is close to the center of the discharge cell is connected to the first projecting electrode  402   c ,  403   c , forming a path where a discharge diffusion is initiated with the beginning of the discharge. The electrode line  402   b ,  403   b  which is far from the center of the discharge cell is connected to the second projecting electrode  402   e ,  403   e . The electrode line  402   b ,  403   b  which is far from the center of the discharge cell plays the role of diffusing a discharge to the peripheral of the discharge cell. 
     The first projecting electrode  402   c ,  403   c  is connected to the electrode line  402   a ,  403   a  which is close to the center of the discharge cell in one discharge cell, and protruding to the center of the discharge cell. Preferably, the first projecting electrode  402   c ,  403   c  is formed in the center of the electrode line  402   a ,  403   a . The first projecting electrode  402   c ,  403   c  can effectively lower the firing voltage of the plasma display panel with forming in the center of the electrode line  402   a ,  403   a.    
     It is preferable that the width W 1  of the projecting electrode  402   c ,  403   c  ranges from 35 μm to 45 μm, while the gap between the projecting electrodes  402   c ,  403   c  ranges from 15 μm to 165 μm. The critical meaning of the upper limit value and the lower limit value of the width and the gap of the projecting electrode  402   c ,  403   c  will be omitted since it is identical with the description illustrated in  FIG. 3 . 
     The bridge electrodes  402   d ,  403   d  connect two electrode lines  402   a  and  402   b ,  403   a  and  403   b  forming the sustain electrode  402 ,  403  respectively. The bridge electrode  402   d ,  403   d  helps the generated discharge to be easily diffused to the center of the discharge cell and the remote electrode line  402   b ,  403   b  through the projecting electrode. Here, bridge electrode  402   d ,  403   d  is positioned in the discharge cell, however, if necessary, it can be formed on the barrier rib  412  partitioning off the discharge cell. 
     Accordingly, in the second embodiment of the electrode structure of the plasma display panel according to the present invention, a discharge can be diffused to the space between the electrode line  402   b ,  403   b  and the barrier rib  412 . Therefore, the luminous efficiency of the plasma display panel can be improved by increasing the discharge diffusion efficiency. 
     The second projecting electrodes  402   e ,  403   e  are connected to the electrode line  402   b ,  403   b  which is far from the center of the discharge cell, and protruding to the opposite direction of the center of the discharge cell. It is preferable that the length of the second projecting electrode  402   e ,  403   e  ranges from 30 μm to 100 μm. 
     Thus, a discharge can be effectively diffused to the discharge space which is far from the center of the discharge cell. To maintained the aperture ratio of the panel with 25% to 45%, thereby, at the same time, to improve the luminance of the display image, the length of the second projecting electrode  402   e ,  403   e  may range from 50 μm to 100 μm. 
     As shown in  FIG. 5   a , the second projecting electrode  402   e ,  403   e  can be extended to the barrier rib  412  partitioning off the discharge cell. In addition, if the aperture ratio can be fully compensated in the other part, the second projecting electrode  402   e ,  403   e  can be partly extend on the barrier rib  412  so as to much more improve the discharge diffusion efficiency. 
     However, in case the second projecting electrode  402   e ,  403   e  is not extended to the barrier rib  412 , it is preferable that the gap between the second projecting electrode  402   e ,  403   e  and the barrier rib  412  which is adjacent to the second projecting electrode  402   e ,  403   e  is 70 μm or less. 
     When the gap between the second projecting electrode  402   e ,  403   e  and the barrier rib  412  is 70 μm or less, a discharge can be diffused effectively to the discharge space which is far from the center of the discharge cell. 
     It is preferable that, in the second embodiment of the present invention, the second projecting electrode  402   e ,  403   e  is formed in the center of electrode line  402   b ,  403   b  to evenly diffuse a discharge over the peripheral of the discharge cell. 
     In the meantime, in the second embodiment of the present invention, it is preferable that the width Wb of the barrier rib positioned in the direction to which the second projecting electrode  402   e ,  403   e  is extended among the barrier ribs partitioning off the discharge cell is 200 μm or less. 
     In addition, it is preferable that a black matrix (not shown) for absorbing the external light to obtain the bright room contrast and preventing the emitted discharge light from being diffused throughout the neighboring discharge cell to display is formed on the barrier rib  412 . 
     The width of the barrier rib  412  is suggested to be 200 μm or less, thereby, the region of the discharge cell is increased. Accordingly, the luminous efficiency can be increased, and the reduction of the aperture ratio due to the second projecting electrode can be compensated. Preferably, the width Wb of the barrier rib positioned in the direction to which the second projecting electrode is extended ranges from 90 μm to 100 μm to obtain the optimum luminous efficiency. 
     It is preferable that the aperture ratio of the plasma display panel according to the present invention ranges from 25% to 45% so as to improve the luminance of the display image and the contrast, and to obtain the resistance value of the electrode for obtaining the drive margin of the drive panel. 
     It is preferable that the aperture ratio of the panel is an aperture ratio on the basis of the effective display region of a panel, that is, the region where the discharge cells which affect on the display image of the panel among the discharge cells of the panel is positioned. 
     Referring to  FIG. 5   b , the protrusion  403   c  can include a curved portion having a curvature. As shown in  FIG. 5   b , in case the protrusion  403   c  is formed with a curve shape, the manufacturing process of the electrode can be more facilitated. In addition, such shape can prevent the wall charges from being excessively concentrated on a specific location in driving the panel. Accordingly, the discharge characteristic is stabilized, and the driving stability can be improved. 
     As shown in  FIG. 5   b , in case the protrusion  403   c  is formed with a curve shape, it is preferable that the width W of the protrusion  403   c  is defined as the width of the center portion of the protrusion  403   c . In addition, the portion in which the bridge electrode  402   d ,  403   d  and the electrode line  402   a ,  403   a  are connected has a curvature like the protrusion  403   c  shown in  FIG. 5   b.    
       FIG. 6  is a cross-sectional view showing a third embodiment of the electrode structure of a plasma display panel according to the present invention. The same description described in  FIG. 5   a  to  FIG. 5   b  among the electrode structure shown in  FIG. 6  will be omitted. 
     As shown in  FIG. 6 , in the third embodiment of the electrode structure according to the present invention, two first projecting electrodes  602   a ,  603   a  are formed in the sustain electrode  602 ,  603  respectively. The first projecting electrodes  602   a ,  603   a  are connected to the electrode line which is close to the center of the discharge cell, and protruding to the direction of the center of the discharge cell. Preferably, each first projecting electrodes  602   a ,  603   a  is symmetrized based on the center of the electrode line to be formed. 
     It is preferable that the width of the first projecting electrodes  602   a ,  603   a  ranges from 35 μm to 45 μm. The critical meaning of the upper limit value and the lower limit value of the width of the projecting electrodes will be omitted since it is identical with the description illustrated in  FIG. 3 . 
     It is preferable that the gap d 1 , d 2  of the first projecting electrodes protruded from one electrode line ranges from 50 μm to 100 μm in case the plasma display panel has the size of 42 inch with the resolution of VGA. In case the plasma display panel has the size of 42 inch with the resolution of XGA, it is preferable that the gap d 1 , d 2  of the first projecting electrode ranges from 30 μm to 80 μm. In case the plasma display panel has the size of 50 inch with the resolution of XGA, it is preferable that the gap d 1 , d 2  of the first projecting electrode ranges from 40 μm to 90 μm. 
     When the gap d 1 , d 2  of the first projecting electrode has such range, the aperture ratio capable of implementing the luminance of the image required for the display device can be obtained. Also, the power used up in displaying can be prevented from being increased over the threshold level, when the power is increased as the reactive power due to the first projecting electrode which is so close to the barrier rib is increased. 
     Two first projecting electrodes  602   a ,  603   a  are formed on the sustain electrode  602 ,  603  such that the electrode region in the center of the discharge cell is increased. Accordingly, before a discharge is generated, the space charge is very much formed in the discharge cell, thereby, the firing voltage is more decreased, and the discharge rate is increased. Additionally, after the discharge is generated, the amount of wall charges are increased such that the luminance rises, and the discharge is uniformly diffused throughout the whole discharge cell. 
     It is preferable that the gap a 1 , a 2  of the first projecting electrodes  602   c ,  603   c , that is, the gap of two projecting electrodes in the direction intersecting with the electrode line  602 ,  603  ranges from 15 μm to 165 μm. The critical meaning of the upper limit value and the lower limit value of the gap of the projecting electrodes will be omitted since it is identical with the description illustrated in  FIG. 3 . 
       FIG. 7  is a cross-sectional view showing a fourth embodiment of the electrode structure of a plasma display panel according to the present invention. The same description described in  FIG. 5 ,  FIG. 6  among the electrode structure shown in  FIG. 7  will be omitted. 
     As shown in  FIG. 7 , in the fourth embodiment of the electrode structure according to the present invention, three first projecting electrodes  702   a ,  703   a  are formed in the sustain electrode  702 ,  703  respectively. 
     The first projecting electrodes  702   a ,  703   a  are connected to the electrode line which is close to the center of the discharge cell, and protruding to the direction of the center of the discharge cell. Preferably, one of first projecting electrodes is formed in the center of the discharge cell, and the other, two electrodes, are symmetrized based on the center of the electrode line to be formed. 
     Three first projecting electrodes  702   a    703   a  are formed on the sustain electrode  702 ,  703  respectively. Thus, the firing voltage is much more decreased than  FIG. 5  and  FIG. 6 , and the discharge rate is much more increased. Additionally, after a discharge is generated, the luminance is much more increased, and the discharge is more uniformly diffused throughout the whole discharge cell. 
     As described in the above, by increasing the number of the first projecting electrode, the electrode region in the center of the discharge cell increases such that the firing voltage is decreased and a luminance increases. On the other hand, it should be considered that the brightest discharge light is emitted while the strongest discharge occurs in the center of the discharge cell. That is, by blocking the light emitted in the center of the discharge cell as the number of the first projecting electrode increases, the emitted light remarkedly reduces. Furthermore, additionally considering the firing voltage and the luminous efficiency at the same time, the most optimal number is selected to design the structure of the sustain electrode. 
     It is preferable that the width of the first projecting electrodes  702   a ,  703   a  ranges from 35 μm to 45 μm, while the gap a 1 , a 2 , a 3  of the first projecting electrodes  702   c ,  703   c  ranges from 15 μm to 165 μm. The critical meaning of the upper limit value and the lower limit value of the gap and the width of the projecting electrodes will be omitted since it is identical with the description illustrated in  FIG. 3 . 
       FIG. 8  is a cross-sectional view showing a fifth embodiment of the electrode structure of a plasma display panel according to the present invention. 
     Each sustain electrode  800 ,  810  includes three electrode lines  800   a ,  800   b ,  800   c ,  810   a ,  810   b ,  810   c  crossing the discharge cell. The electrode lines are extended to one direction of the plasma display panel with crossing the discharge cell. The width of the electrode lines is narrowly formed to increase the aperture ratio. Preferably, the width of the electrode lines ranges from 20 μm to 70 μm such that the aperture ratio can be improved and a discharge can be smoothly occurred. 
     It is preferable that the thickness of the electrode lines  800   a ,  800   b ,  800   c ,  810   a ,  810   b ,  810   c  of the sustain electrode pair ranges from 3 μm to 7 μm. The gap a 1 , a 2  of the electrode lines of three electrode lines forming the sustain electrode can be identical or different, while the width b 1 , b 2 , b 3  of the electrode lines can be identical or different. 
     The critical meaning of the upper limit value and the lower limit value of the thickness of the electrode lines will be omitted since it is identical with the description illustrated in  FIG. 2   a.    
       FIG. 9  is a cross-sectional view showing a sixth embodiment of the electrode structure of a plasma display panel according to the present invention. 
     Each sustain electrode  900 ,  910  includes four electrode lines  900   a ,  900   b ,  900   c ,  900   d ,  910   a ,  910   b ,  910   c ,  910   d  crossing the discharge cell. The electrode lines are extended to one direction of the plasma display panel with crossing the discharge cell. The width of the electrode lines is narrowly formed to increase the aperture ratio. Preferably, the width of the electrode lines ranges from 20 μm to 70 μm such that the aperture ratio can be improved and a discharge can be smoothly occurred. 
     It is preferable that the thickness of the electrode lines  900   a ,  900   b ,  900   c ,  900   d ,  910   a ,  910   b ,  910   c ,  910   d  of the sustain electrode pair ranges from 3 μm to 7 μm. The critical meaning of the upper limit value and the lower limit value of the thickness of the electrode lines will be omitted since it is identical with the description illustrated in  FIG. 2   a.    
     The gap c 1 , c 2 , c 3  of the electrode lines of four electrode lines forming the sustain electrode can be identical or different, while the width d 1 , d 2 , d 3 , d 4  of the electrode lines can be identical or different. 
       FIG. 10  is a cross-sectional view showing a seventh embodiment of the electrode structure of a plasma display panel according to the present invention. 
     Each sustain electrode  1000 ,  1010  includes four electrode lines  1000   a ,  1000   b ,  1000   c ,  1000   d ,  1010   a ,  1010   b ,  1010   c ,  1010   d  crossing the discharge cell. The electrode lines are extended to one direction of the plasma display panel with crossing the discharge cell. It is preferable that the thickness of the electrode lines  1000   a ,  1000   b ,  1000   c ,  1000   d ,  1010   a ,  1010   b ,  1010   c ,  1010   d  of the sustain electrode pair ranges from 3 μm to 7 μm. The critical meaning of the upper limit value and the lower limit value of the thickness of the electrode lines will be omitted since it is identical with the description illustrated in  FIG. 2   a.    
     The bridge electrodes  1020 ,  1030 ,  1040 ,  1050 ,  1060 ,  1070  connect two electrode lines respectively. The bridge electrode  1020 ,  1030 ,  1040 ,  1050 ,  1060 ,  1070  helps the generated discharge to be easily diffused to the center of the discharge cell and the remote electrode line. As shown in  FIG. 10 , the location of the bridge electrodes  1020 ,  1030 ,  1040 ,  1050 ,  1060 ,  1070  may not coincide, while one of bridge electrodes  1040  can be positioned on the barrier rib  1080 . 
       FIG. 11  is a cross-sectional view showing a eighth embodiment of the electrode structure of a plasma display panel according to the present invention. The bridge electrode connecting electrode lines is formed, differently with  FIG. 10 . That is, one bridge electrode  1120 ,  1130  connecting four electrode lines  1100   a ,  110   b ,  1100   c ,  1100   d ,  1110   a ,  1110   b ,  1110   c ,  1110   d  to each sustain electrode  1100 ,  1110  is formed. 
     It is preferable that the thickness of the electrode lines  1000   a ,  1000   b ,  1000   c ,  1000   d ,  1010   a ,  1010   b ,  1010   c ,  1010   d  of the sustain electrode pair ranges from 3 μm to 7 μm. The critical meaning of the upper limit value and the lower limit value of the thickness of the electrode lines will be omitted since it is identical with the description illustrated in  FIG. 2   a.    
       FIG. 12  is a cross-sectional view showing a ninth embodiment of the electrode structure of a plasma display panel according to the present invention. 
     Projecting electrodes  1220 ,  1230  including a closed loop for each electrode line  1200 ,  1210  are formed. The firing voltage can be lowered by projecting electrodes  1220 ,  1230  including the closed loop as shown in  FIG. 12 , and, at the same time, the aperture ratio can be improved. The form of the projecting electrode and the closed loop can be variously formed. 
     It is preferable that the thickness of the electrode lines  1200 ,  1210  of the sustain electrode pair ranges from 3 μm to 7 μm. The critical meaning of the upper limit value and the lower limit value of the thickness of the electrode lines will be omitted since it is identical with the description illustrated in  FIG. 2   a.    
     It is preferable that the width W 1 , W 2  of the projecting electrodes  1220 ,  1230  ranges from 35 μm to 45 μm. In case the width W 1 , W 2  of the projecting electrode  1220 ,  1230  has such value, by obtaining a sufficient aperture ratio, the light reflected to the front of the plasma display apparatus can be prevented from the reduction of luminance of an image resulting from the blocking of the electrode, 
     It is preferable that the gap of projecting electrode  1220 ,  1230  ranges from 15 μm to 165 μm. The critical meaning of the upper limit value and the lower limit value of the gap of projecting electrode will be omitted since it is identical with the description illustrated in  FIG. 3 . 
       FIG. 13  is a cross-sectional view showing a tenth embodiment of the electrode structure of a plasma display panel according to the present invention. 
     Projecting electrodes  1320 ,  1330  including a rectangular loop for each electrode line  1300 ,  1310  are formed. It is preferable that the thickness of the electrode lines  1320 ,  1330  of the sustain electrode pair ranges from 3 μm to 7 μm. The critical meaning of the upper limit value and the lower limit value of the thickness of the electrode lines will be omitted since it is identical with the description illustrated in  FIG. 2   a.    
     It is preferable that the width W 1 , W 2  of the projecting electrodes  1320 ,  1330  ranges from 35 μm to 45 μm. The critical meaning of the upper limit value and the lower limit value of the width W 1 , W 2  of the projecting electrodes  1320 ,  1330  will be omitted since it is identical with the description illustrated in  FIG. 12 . 
     It is preferable that the gap of projecting electrode  1320 ,  1330  ranges from 15 μm to 165 μm. The critical meaning of the upper limit value and the lower limit value of the gap of projecting electrode will be omitted since it is identical with the description illustrated in  FIG. 3 . 
       FIG. 14   a  and  FIG. 14   b  are a cross-sectional view showing a eleventh embodiment of the electrode structure of a plasma display panel according to the present invention. For each electrode line  1400 ,  1410 , first projecting electrodes  1420   a ,  1420   b ,  1430   a ,  1430   b  protruding to the direction of the center of the discharge cell and second projecting electrodes  1440 ,  1450 ,  1460 ,  1470  protruding to the direction of the center of the discharge cell or in the opposite direction of the center of the discharge cell are formed. 
     As shown in  FIG. 14   a , it is preferable that, for each electrode line  1400 ,  1410 , two first projecting electrodes  1420   a ,  1420   b ,  1430   a ,  1430   b  protruding to the direction of the center of the discharge cell are formed respectively, while one second projecting electrode  1440 ,  1450  protruding to the opposite direction of the center of the discharge cell is formed. Further, as shown in  FIG. 14   b , the second projecting electrode  1460 ,  1470  can be protruded to the center of the discharge cell. 
     It is preferable that the thickness of the electrode lines  1400 ,  1410  of the sustain electrode pair ranges from 3 μm to 7 μm. The critical meaning of the upper limit value and the lower limit value of the thickness of the electrode lines will be omitted since it is identical with the description illustrated in  FIG. 2   a.    
     It is preferable that the width of the first projecting electrodes  1420   a ,  1420   b ,  1430   a ,  1430   b  ranges from 35 μm to 45 μm. The critical meaning of the upper limit value and the lower limit value of the width of the projecting electrodes will be omitted since it is identical with the description illustrated in  FIG. 4 . 
     it is preferable that the gap d 1 , d 2  of the two first projecting electrodes protruded from one electrode line ranges from 50 μm to 100 μm in case the plasma display panel has the size of 42 inch with the resolution of VGA. In case the plasma display panel has the size of 42 inch with the resolution of XGA, it is preferable that the gap d 1 , d 2  of the first projecting electrode ranges from 50 μm to 100 μm. In case the plasma display panel has the size of 50 inch with the resolution of XGA, it is preferable that the gap d 1 , d 2  of the first projecting electrode ranges from 40 μm to 90 μm. 
     The critical meaning of the upper limit value and the lower limit value of the gap d 1 , d 2  of the first projecting electrode will be omitted since it is identical with the description illustrated in  FIG. 6 . 
     It is preferable that the gap of another first projecting electrodes, that is, the gap a 1  between  1420   a  and  1430   a , or the gap a 2  between  1420   b  and  1430   b  ranges from 15 μm to 165 μm. The critical meaning of the upper limit value and the lower limit value of the gap of the projecting electrodes will be omitted since it is identical with the description illustrated in  FIG. 3 . 
       FIG. 15  is a drawing showing an embodiment of the method in which a frame of an image of a plasma display panel is time-divided into a plurality of subfields for driving in according to the present invention having the structure described above. 
     The unit frame can be time-divided driven with a predetermined number, for example, eight subfields SF 1 , SF 8  so as to express the gray level of an image. Further, each subfield SF 1 , . . . , SF 8  is divided into a reset period (not shown), an address period A 1 , . . . , A 8 , and a sustain period S 1 , . . . , S 8 . 
     In each address period A 1 , . . . , A 8 , a data signal is applied to the address electrode X, while a scan pulse corresponding to it is sequentially applied to each scan electrode Y. In each sustain period S 1 , . . . , S 8 , the sustain pulse is alternately applied to the scan electrode Y and the sustain electrode Z such that the sustain discharge is generated in discharge cells selected in the address period Al, . . . , A 8 . 
     The luminance of the plasma display panel is in proportion to the number of sustain discharge pulse of the sustain period S 1 , . . . , S 8  in the unit frame. In case one frame forming one image is expressed with 8 subfields and 256 gray level, the sustain pulse having a different number can be allocated to each subfield with the rate of 1, 2, 4, 8, 16, 32, 64, 128. To obtain the luminance of 133 gray level, cells are addressed to generate a sustain discharge during the subfield  1  period, the subfield  3  period, and the subfield  8  period. 
     In the meantime, according to the weighted value of the subfields by Automatic Power Control APC step, the number of sustain discharge allocated to each subfield can be variably determined. That is, in  FIG. 15 , it was exemplified that a frame is divided into 8 subfields. However, the invention is not restricted to that. Hence, the number of the subfield forming a frame can be variously changed according to the design type. For example, it can be divided into below or over 8 subfields such as 12 subfields or 16 subfields to drive the plasma display panel. 
     In addition, the number of sustain discharge allocated to each subfield can be variously changed in consideration of the gamma characteristics or the panel characteristics. For example, the gray level allocated to the subfield  4  can be lowered from 8 to 6, while the gray level allocated to the subfield  6  can be enhanced from 32 to 34. 
     Pre reset period exists to form positive wall charges on the scan electrode Y and to form positive wall charge on the sustain electrode Z. Thereafter, by using the wall charge distribution formed by the pre reset period, each subfield includes a reset period for initializing the discharge cells of the full screen, an address period for selecting the discharge cell, and a sustain period for maintaining the discharge of the selected discharge cells. 
     The reset period is comprised of a setup period and a set down period. In the set up period, ramp-up waveforms are simultaneously supplied to all the scan electrodes to generate a micro discharge in the discharge cell. Accordingly, the wall charges are generated. 
     In the set down period, at the same time, the ramp-down waveforms falling from the positive polarity voltage lower than the peak voltage of the ramp-up waveform are simultaneously supplied to all of the scan electrodes Y to generate an erase discharge in all discharge cells. Accordingly, electric charges which are not necessary are deleted among the wall charge generated by the set up discharge and the space charge. 
     In the address period, the scan signal scan of the negative polarity is sequentially supplied to the scan electrode, while, simultaneously, the data signal data of the positive polarity is supplied to the address electrode X. The address discharge is generated and a cell is selected due to the voltage difference between the scan signal scan and the data signal data and the wall voltage generated during the reset period. 
     In the meantime, during the set down period and the address period, a signal maintaining the sustain voltage Vs is supplied to the sustain electrode. 
     In the sustain address, the sustainer pulse is alternately supplied to the scan electrode and the sustain electrode to generate a sustain discharge with a surface discharge type between the scan electrode and the sustain electrode. 
       FIG. 16  is a waveform diagram showing an embodiment of driving signals for driving a plasma display panel, the invention is not restricted by waveforms shown in  FIG. 16 . 
     For example, the pre reset period can be omitted. The polarity and voltage level of the signals shown in  FIG. 16  can be changed, if necessary. The erase signal for the wall charge elimination after the sustain discharge is completed can be supplied to the sustain electrode. In addition, the single sustain drive mode in which the sustain discharge can be supplied to one of the scan electrode Y and the sustain Z electrode to generate a sustain discharge can be used. 
     As described in the above, according to the panel equipped in the plasma display apparatus of the present invention, by removing the transparent electrode consisting of ITO, the manufacturing cost of the plasma display panel can be diminished. By forming projecting electrodes protruded to the opposite direction of the center of the discharge cell or in the direction of the center of the discharge cell from the sustain electrode line or the scan electrode, the firing voltage can be lowered, and the discharge diffusion efficiency in the discharge cell can be increased. 
     It will be apparent to those skilled in the art that various modifications and variation can be made in the present invention without departing from the spirit or scope of the present invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.