Patent Publication Number: US-2006001374-A1

Title: Plasma display panel

Description:
BACKGROUND OF THE INVENTION  
      This application claims the benefit of Korean Patent Application No. 10-2004-0045389, filed on Jun. 18, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.  
      1. Field of the Invention  
      The present invention relates to a plasma display panel (PDP), and more particularly, to a PDP which has a remarkably high transmittance of visible light and thus, an enhanced brightness, in which a stable and efficient discharge can be achieved at a low voltage driving, thereby allowing for low production costs, and which has an extended lifetime since a reduced number of ions collide with fluorescent materials by preventing ion sputtering.  
      2. Description of the Related Technology  
       FIG. 1  is an exploded perspective view of a conventional alternating current, triode-type, surface discharge plasma display panel (PDP)  100 . Referring to  FIG. 1 , the conventional PDP  100  comprises a front panel  110  and a rear panel  120 . The front panel  110  comprises a front substrate  111 , pairs of sustain electrodes  114  including Y electrodes  112  and X electrodes  113  on a rear surface  111   a  of the front substrate  111 , a front dielectric layer  115  covering the sustain electrodes  114 , and a protective layer  116  covering the front dielectric layer  115 .  
      Each of the Y electrodes  112  includes a transparent electrode  112   b  and a bus electrode  112   a , and each of the X electrodes  113  includes a transparent electrode  113   b  and a bus electrode  113   a . The transparent electrodes  112   b  and  113   b  are formed of indium tin oxide (ITO) or the like. The bus electrodes  112   a  and  113   a  are formed of a highly conductive metal.  
      The rear panel  120  comprises a rear substrate  121 , address electrodes  122  on a front surface of the rear substrate  121  intersecting the pairs of sustain electrodes  114 , a rear dielectric layer  123  covering the address electrodes  122 , barrier ribs  130  arranged on the rear dielectric layer  123  and dividing a discharge space into discharge cells  126 , and fluorescent layers  125  arranged in the discharge cells  126 .  
      In the conventional PDP  100 , in addition to the pairs of the sustain electrodes  114  which generate a discharge, the front dielectric layer  115  and the protective layer  116  are formed on the rear surface  111   a  of the front substrate  111  through which visible light generated from the fluorescent layers  125  is transmitted. Thus, the brightness of the PDP  100  is reduced since the transmittance of visible light is remarkably low due to at least partial blocking of a visible light path by the sustain electrodes  114 , the front dielectric layer  115  and the protective layer  116 .  
      Further, the majority of the sustain electrodes  114  (i.e., the transparent electrodes  112   b  and  113   b , excluding the bus electrodes  112   a  and  113   a ) are formed of ITO, which is highly resistive, in order to allow the generated visible light to be transmitted through the front substrate  111 . However, the ITO electrodes have higher resistance than other metal electrodes.  
      Due to the use of the ITO electrodes, a driving voltage of the PDP  100  increases and a voltage drop occurs, and thus, images cannot be uniformly displayed.  
      Furthermore, in the conventional PDP  100 , the pairs of sustain electrodes  114  are formed on the rear surface  111   a  of the front substrate  111 , through which visible light is transmitted, and the discharge occurs behind the protective layer  116  and diffuses within the discharge cells  126 . In other words, the discharge occurs only in a portion of the discharge cells  126  and a space in the discharge cells  126  cannot be efficiently utilized.  
      As a result, a driving voltage for discharging must be increased, and thus, the manufacturing costs of a driving circuit, which is the most expensive part of the PDP  100 , are increased. Further, due to the concentration of the discharge in a limited space in the discharge cells  126 , efficiency of the PDP  100  is reduced.  
      Furthermore, since the pairs of sustain electrodes  114  are formed on the rear surface  111   a  of the front substrate  111  and the discharge occurs behind the front dielectric layer  115  and diffuses toward the fluorescent layers  125 , when the conventional PDP  100  is used for a long time, charged discharge gas induces ion sputtering of the fluorescent material in the fluorescent layers  125  due to the electric field, thereby resulting in permanent after-images, that is to say images shown due to permanent damages of the fluorescent layers  125 .  
     SUMMARY OF CERTAIN INVENTIVE ASPECTS  
      One aspect of the present invention provides a plasma display panel (PDP) having the following advantages.  
      In one embodiment, the transmittance of visible light emitted from fluorescent layer is increased, thereby increasing the brightness of the PDP.  
      In another embodiment, a discharge uniformly occurs in discharge corner portions of discharge cells and is concentrated in the centers of the discharge cells, thereby allowing for a stable and efficient discharge at a low-voltage driving. As a result, the manufacturing costs of integrated circuit chips driving the PDP are reduced and thus, the overall production costs of the PDP are decreased.  
      In another embodiment, the use of ITO electrodes is excluded, and thus, the production costs of the PDP are reduced and a screen area of the PDP is increased.  
      In another embodiment, an acceleration path of ion particles is changed from the discharge corner portions of the discharge cells to the centers of the discharge cells and the number of the ions colliding with fluorescent materials is reduced, thereby preventing ion sputtering, and thus extending the lifetime of the PDP.  
      Another aspect of the present invention provides a PDP comprising: a front substrate and a rear substrate facing each other; barrier ribs made of a dielectric material and arranged between the front substrate and the rear substrate to define discharge cells in which a discharge occurs; first electrodes arranged in the barrier ribs to surround first corner portions of the discharge cells; second electrodes arranged in the barrier ribs to surround second corner portions of the discharge cells, the second corner portions being diagonally opposite to the first corner portions surrounded by the first electrodes, and the second electrodes facing the first electrodes in the discharge cells and being separated from the first electrodes; fluorescent layers arranged in the discharge cells; and a discharge gas provided in the discharge cells.  
      In one embodiment, the first electrodes may extend in the same direction as the discharge cells and the second electrodes may extend parallel to the direction in which the first electrodes extend.  
      In this embodiment, the first electrodes may have first electrode protruding portions which protrude to cross the direction in which the first electrodes extend such that the first electrodes surround the first corner portions of the discharge cells. Furthermore, the second electrodes may have second electrode protruding portions which protrude to cross the direction in which the second electrodes extend and face the first electrode protruding portions in the discharge cells such that the second electrodes surround the second corner portions of the discharge cells.  
      In one embodiment, the PDP may further comprise address electrodes crossing the direction in which the first electrodes and the second electrodes extend.  
      In one embodiment, the address electrodes may be arranged on the rear substrate and a dielectric layer may be arranged on the rear substrate to cover the address electrodes. The fluorescent layers may be arranged in spaces defined by the dielectric layer and the barrier ribs.  
      In one embodiment, the first electrodes may extend in the same direction as the discharge cells and the second electrodes may extend to cross the direction in which the first electrodes extend.  
      In this embodiment, the first electrodes may have first electrode protruding portions which protrude parallel to the direction in which the second electrodes extend in the discharge cells such that the first electrodes surround the first corner portions of the discharge cells. Furthermore, the second electrodes may have second electrode protruding portions which protrude parallel to the direction in which the first electrodes extend in the discharge cells and face the first electrode protruding portions in the discharge cells such that the second electrodes surround the second corner portions of the discharge cells.  
      In one embodiment, the PDP may further comprise protective layers arranged on at least portions of the barrier ribs.  
      In one embodiment, the barrier ribs may comprise central barrier rib portions and side barrier rib portions and the first electrodes and the second electrodes may be arranged on sidewalls of the central barrier rib portions and contacted by the side barrier rib portions.  
      In this embodiment, a dielectric material of the central barrier rib portions may have a lower dielectric constant than a dielectric material of the side barrier rib portions.  
      In one embodiment, the barrier ribs may comprise front barrier ribs and rear barrier ribs and the first electrodes and the second electrodes may be arranged in the front barrier ribs.  
      In this embodiment, the fluorescent layers may be arranged in spaces defined by the rear barrier ribs and the rear substrate. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above and other features and advantages of embodiments of the present invention will be described with reference to the attached drawings.  
       FIG. 1  is an exploded perspective view of a conventional alternating current, triode-type, surface discharge plasma display panel (PDP).  
       FIG. 2  is an exploded perspective view of a PDP according to an embodiment of the present invention.  
       FIG. 3  is a plan view taken along line III-III of the PDP illustrated in  FIG. 2 , showing the positions of first electrodes, second electrodes, address electrodes, and discharge cells.  
       FIG. 4  is a perspective view of first electrodes, second electrodes, and address electrodes of the PDP illustrated in  FIG. 2 .  
       FIG. 5  is a cross-sectional view taken along line V-V of the PDP illustrated in  FIG. 2 , showing an address electrode.  
       FIGS. 6 through 8  are plan views illustrating the operation of the PDP illustrated in  FIG. 2 .  
       FIG. 9  is an exploded perspective view of a PDP according to another embodiment of the present invention.  
       FIG. 10  is a plan view taken along line X-X of the PDP illustrated in  FIG. 9 , showing the positions of first electrodes, second electrodes, and discharge cells.  
       FIG. 11  is a perspective view of first electrodes and second electrodes of the PDP illustrated in  FIG. 9 .  
       FIG. 12  is an exploded perspective view of a PDP according to still another embodiment of the present invention.  
       FIG. 13  is an exploded perspective view of a PDP according to yet another embodiment of the present invention.  
    
    
     DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS  
      Hereinafter, a plasma display panel (PDP) according to embodiments of the present invention will be described by examples with reference to the attached drawings.  
       FIG. 2  is an exploded perspective view of a PDP  200  according to an embodiment of the present invention.  FIG. 3  is a plan view taken along line III-III of the PDP  200  illustrated in  FIG. 2 . Referring to  FIGS. 2 and 3 , the PDP  200  comprises a front panel  210  and a rear panel  220 . The front panel  210  comprises a front substrate  211 , and the rear panel  220  comprises a rear substrate  221 .  
      Barrier ribs  230  are arranged between the front panel  210  and the rear panel  220  to define discharge cells  226  in which a discharge occurs to generate light for displaying images. In one embodiment, the discharge cells  226  comprise first corner portions  226   b , second corner portions  226   a  diagonally opposite to the first corner portions  226   b , and discharge corner portions  226   c  and  226   d . In one embodiment, the barrier ribs  230  may comprise front barrier ribs  215  and rear barrier ribs  224  which may be formed separately during the manufacturing process.  
      The front barrier ribs  215  are arranged on a rear surface of the front substrate  211  to define the discharge cells  226  together with the front substrate  211  and the rear substrate  221 . The front panel  210  comprises discharge electrodes  219  which comprise first electrodes  213  and second electrodes  212 . In one embodiment, the first electrodes  213  are arranged in the barrier ribs  230  such that they surround the first corner portions  226   b  of the discharge cells  226 . In one embodiment, the second electrodes  212  are arranged in the barrier ribs  230  such that they surround the second corner portions  226   a  of the discharge cells  226 , the second corner portions  226   a  being diagonally opposite to the first corner portions  226   b  surrounded by the first electrodes  213 , the second electrodes  212  facing the first electrodes  213  in the discharge cells  226  and separated from the first electrodes  213 .  
      Referring to  FIG. 3 , the first electrodes  213  extend in a predetermined direction and more specifically, in the x-axis direction, and the second electrodes  212  extend in the x-axis direction to be parallel to the direction in which the first electrodes  213  extend.  
      In one embodiment, the first electrodes  213  comprise first electrode protruding portions  213   a  and first electrode extending portions  213   b . The first electrode protruding portions  213   a  protrude to cross the direction in which the first electrodes  213  extend, i.e., protrude in the −y-axis direction of  FIG. 3 , such that the first electrodes  213  surround the first corner portions  226   b  of the discharge cells  226 . The second electrodes  212  may comprise second electrode protruding portions  212   a  and second electrode extending portions  212   b . The second electrode protruding portions  212   a  protrude to cross the direction in which the second electrodes  212  extend, i.e., protrude in the y-axis direction of  FIG. 3 , and face the first electrode protruding portions  213   a  in the discharge cells  226  such that the second electrodes  212  surround the second corner portions  226   a  of the discharge cells  226 , the second corner portions  226   a  being diagonally opposite to the first corner portions  226   b  surrounded by the first electrodes  213 .  
      The front panel  210  may comprise protective layers  216  covering outer sidewalls  215   g  of the front barrier ribs  215 , if necessary. The protective layers  216  may be formed on the rear surface of the front substrate  211  or front surfaces  225   a  of fluorescent layers  225 , in addition to the outer sidewalls  215   g  of the front barrier ribs  215 .  
      In one embodiment, the rear panel  220  comprises address electrodes  222  arranged on a front surface  221   a  of the rear substrate  221  and extending to cross the discharge electrodes  219 , and more specifically, extending in the y-axis direction to cross the discharge cells  226 . The rear panel  220  may comprise a dielectric layer  223  covering the address electrodes  222 . The rear panel  220  comprises the rear barrier ribs  224  formed on the dielectric layer  223  and the fluorescent layers  225  arranged in spaces defined by the rear barrier ribs  224 . Since the fluorescent layers  225  are arranged to cover the address electrodes  222 , the dielectric layer  223  can be omitted. However, in order to prevent the address electrodes  222  from being damaged during the formation of the barrier ribs  230  or to perform an efficient address discharge, for example, by increasing the amount of wall charges accumulated during the address discharge, in one embodiment, the rear panel  220  comprises the dielectric layer  223 .  
      In one embodiment, the front panel  210  and the rear panel  220  may be combined with each other using a combination member, such as a frit (not shown) and sealed. Alternatively, when a discharge gas in the discharge cells  226  is in a vacuum state, the front panel  210  and the rear panel  220  are pressed against each other by the pressure due to the vacuum state, thereby reinforcing the combination thereof.  
      The discharge cells  226  are filled with a discharge gas, such as neon (Ne), helium (He), argon (Ar), each containing xenon (Xe) gas, or a mixture thereof.  
      In one embodiment, the front substrate  211  and the rear substrate  221  are generally made of glass. In another embodiment, the front substrate  211  may be made of a material having a high light transmittance. In still another embodiment, the rear substrate  221  is made of a transparent material since the rear substrate  221  is not in an optical path of the visible light.  
      In one embodiment, the PDP  200  does not include elements of the conventional PDP  100  illustrated in  FIG. 1  such as the sustain electrodes  114  on the rear surface of the front substrate  111 , the front dielectric layer  115  covering the sustain electrodes  114 , and the protective layer  116  covering the front dielectric layer  115 , in a portion of the rear surface of the front substrate  211 , which defines the discharge cells  226 . Thus, when considering only the PDP  200 , excluding, for example, a filter arranged in the front of the PDP  200 , the visible light generated by the fluorescent layers  225  is transmitted only through the transparent front substrate  211 , which has a high light transmittance, thereby greatly increasing the transmittance of the visible light, compared to the conventional PDP  100 .  
      In one embodiment, in order to increase the brightness of the PDP  200 , a reflective layer (not shown) may be arranged on the front surface  221   a  of the rear substrate  221  or the front surface  223   a  of the dielectric layer  223 , or a light reflective material may be contained in the dielectric layer  223  such that the visible light generated by the fluorescent layers  225  is efficiently reflected forward.  
      In the conventional alternating current, triode-type, surface discharge PDP  100 , in order to increase the transmittance of visible light, the first electrodes  213  and the second electrodes  212  are made of ITO, which has a relatively high resistance. However, in one embodiment as illustrated in  FIG. 2 , the first electrodes  213  and the second electrodes  212  can be made of a material having any level of transmittance of visible light.  
      In one embodiment, the first electrodes  213  and the second electrodes  212  can be made of materials which are inexpensive and have high electrical conductivity, such as Ag, Cu, Cr, etc. Therefore, in this embodiment, the problems that appear in the conventional PDP  100 , i.e., the increase in a driving voltage by ITO sustain electrodes and the impossibility to display uniform images due to the voltage drop in the ITO electrodes when the conventional PDP  100  is large, can be overcome and the production costs of the PDP  200  can be reduced.  
      The barrier ribs  230  are arranged between the front substrate  211  and the rear substrate  221  to define the discharge cells  226  together with the front substrate  211  and the rear substrate  221 . In one embodiment, the discharge cells  226  are defined into a matrix shape by the barrier ribs  230  in  FIG. 2 , but are not limited thereto, and may have various shapes, for example, a honeycomb or delta shape.  
      In one embodiment, the cross-sections of the discharge cells  226  are rectangular in  FIG. 2 , but are not limited thereto. In another embodiment, the discharge cells  226  may have smoothly curved surfaces. In another embodiment, especially, after a baking process for forming the barrier ribs  230 , the cross-sections of the discharge cells  226  are oval, rather than rectangular, since the discharge cells  226  shrink due to the baking.  
      In still another embodiment, the cross-sections of the discharge cells  226  may be polygonal, for example, triangles or pentagons, or circular, oval, etc.  
      For example, when a cross-section of each of the discharge cells  226  is circular or oval, a region near a point on a circumference of a portion of the discharge cell  226  which is divided by an imaginary surface cutting the discharge cell  226  in a direction perpendicular to the cross-section of the discharge cell  226  may be set to a first corner portion. Also, a region near a point opposite to the above point and present on a circumference of the other portion of the discharge cell  226  may be a second corner portion.  
      In one embodiment, the first electrodes  213  and the second electrodes  212  can be arranged to surround the first corner portions  226   b  and the second corner portions  226   a  of the discharge cells  226 , respectively, although the discharge cells  226  have any shape, for example, circular or oval. Thus, although the terms “corner portions” of the discharge cells  226  and “diagonally” are used on the assumption that the cross-sections of the discharge cells  226  are polygonal, the shapes of the cross-sections of the discharge cells  226  may have other forms according to an embodiment of the present invention. In such a situation, the first and second electrodes  213 ,  212  may surround at least in part the first portions  226   b  and the second portions  226   a  of the discharge cells  226 , respectively.  
      The discharge electrodes  219  are arranged in the front barrier ribs  215  and the discharge occurs by applying a potential between the discharge electrodes  219 . In one embodiment, the front barrier ribs  215  should be made of a dielectric material such that an electric field occurring due to the potential applied between the discharge electrodes  219  generated inside the discharge cells  226  by the molecule arrangement of the material of the front barrier ribs  215 .  
      In another embodiment, the front barrier ribs  215  may be made of a dielectric material, such as glass containing elements such as Pb, B, Si, Al, and O, and if necessary, a filler such as ZrO 2 , TiO 2 , and Al 2 O 3  and a pigment such as Cr, Cu, Co, Fe, TiO 2 . Such a dielectric material induces charged particles due to the potential applied between the discharge electrodes  219 , and thus, induces the wall charges which participate in the discharge and protect the discharge electrodes  219 .  
      In one embodiment, after the front barrier ribs  215  are formed, the protective layers  216  (see  FIG. 5 ) may be formed on the outer sidewalls  215   g  of the front barrier ribs  215  by deposition, etc. The protective layers  216  can protect the first electrodes  213 , the second electrodes  212 , and the dielectric layer  223  covering the second electrodes  212 , and emit secondary electrons during the discharge, thereby allowing the discharge to be easily generated.  
      In one embodiment, during the formation of the protective layers  216 , a protective layer may be further formed on the rear surface of the front substrate  211  and on the rear surfaces  215   e  of the front barrier ribs  215 . The protective layer thus formed does not have an adverse effect on the PDP of the present invention.  
      The rear barrier ribs  224  may be formed on the dielectric layer  223 . In one embodiment, the rear barrier ribs  224  may be made of a dielectric material, such as glass containing elements such as Pb, B, Si, Al, and O, and if necessary, a filler such as ZrO 2 , TiO 2 , and Al 2 O 3  and a pigment such as Cr, Cu, Co, Fe, TiO 2 , as in the front barrier ribs  215 .  
      The rear barrier ribs  224  define spaces on which the fluorescent layers  225  are coated and, together with the front barrier ribs  215 , resist the vacuum pressure (for example, 0.5 atm) of the discharge gas filled between the front panel  210  and the rear panel  220 . The rear barrier ribs  224  also define spaces for the discharge cells  226  and prevent cross-talk between the discharge cells  226 . In one embodiment, the rear barrier ribs  224  may contain a reflective material to reflect the visible light generated in the discharge cells  226  forward.  
      The fluorescent layers  225 , which emit red, green, or blue light, may be arranged in the spaces defined by the rear barrier ribs  224 . The fluorescent layers  225  are divided by the rear barrier ribs  224 .  
      The fluorescent layers  225  are formed by coating a fluorescent paste comprising either red, green, or blue light-emitting fluorescent material, a solvent, and a binder, on the front surface  223   a  of the dielectric layer  223  and the outer sidewalls  224   a  of the rear barrier ribs  224 , and drying and baking the resultant structure.  
      In one embodiment, the red light-emitting fluorescent material may be Y(V,P)O4:Eu, etc., the green light-emitting fluorescent material may be ZnSiO 4 :Mn, YBO 3 :Tb, etc., and the blue light-emitting fluorescent material may be BAM:Eu, etc.  
      In one embodiment, the rear protective layers (now shown), made of, for example, MgO, may be formed on the front surfaces  225   a  of the fluorescent layers  225 . When the discharge occurs in the discharge cells  226 , the rear protective layers can prevent deterioration of the fluorescent layers  225  due to collisions of the discharge particles and emit secondary electrons, thereby allowing the discharge to be easily generated. However, the presence of the rear protective layers is not always advantageous. When the rear protective layers are too thick, the transmittance of UV light can be reduced.  
       FIG. 4  is a perspective view of first electrodes  213 , second electrodes  212 , and address electrodes  222  of the PDP  200  illustrated in  FIG. 2 .  
      Referring to  FIG. 4 , the first electrodes  213  extend in the x-axis direction, and the second electrodes  212  extend in the x-axis direction to be parallel to the direction in which the first electrodes  213  extend.  
      As described above, the first electrodes  213  comprise first electrode protruding portions  213   a  which protrude in the −y-axis direction. The second electrodes  212  may comprise second electrode protruding portions  212   a  which protrude in the −y-axis direction and face the first electrode protruding portions  213   a  in the discharge cells  226 .  
      The operation of the PDP  200  illustrated in  FIG. 2  will now be explained briefly referring to  FIGS. 5 through 8 . A driving mode of the PDP  200  is explained on the basis of a particular driving mode, but is not limited thereto. The PDP  200  can be driven according to various driving modes. The following driving mode is only an example to illustrate the concept of the present invention.  
      An address discharge according to an embodiment of the present invention will now be described with reference to  FIG. 5 .  
      In general, the term “address discharge” refers to a discharge for selecting a discharge cell in which a sustain discharge will occur (a sustain discharge will be explained later). The address discharge occurs by applying a pulse potential between a pair of electrodes which cross at a discharge cell where the sustain discharge will occur, to generate a discharge and making wall charges induced by the discharge accumulate on inner surfaces of the discharge cell.  
      Since the electrodes  219  including the first electrodes  213  and the second electrodes  212  are arranged to cross the address electrodes  222 , such an address discharge can occur between the first electrodes  213  and the address electrodes  222  or between the second electrodes  212  and the address electrodes  222 . Herein, it is assumed that the address discharge occurs between the second electrodes  212  and the address electrodes  222 .  
      When a predetermined pulse potential is applied between the address electrodes  222  and the second electrodes  212  from an external power supply, one of the discharge cells  226  to be lighted, at which the second electrodes  212  and the address electrodes  222  cross, is selected. Then, when the potential difference generated due to the pulse potential applied between the second electrodes  212  and the address electrodes  222  reaches a firing voltage, a discharge occurs in the selected discharge cell  226 . Due to the discharge, wall charges are accumulated on the inner surfaces of the selected discharge cell  226 .  
      A sustain discharge of the PDP  200  illustrated in  FIG. 2  will now be described with reference to  FIGS. 6 through 8 . In general, the term “sustain discharge” refers to a discharge for generating a gray scale corresponding to an external image signal in the discharge cell selected by the address discharge.  
      To display a specific gray scale by a sustain discharge, potentials are alternately applied between a pair of the sustain electrodes for a specific number of times. At this time, since the wall charges are accumulated only in the discharge cell selected by the address discharge, a potential applied by the pair of the sustain electrodes interacts with the wall charges, thereby generating the discharge in the selected discharge cell. Such a discharge is repeated a predetermined number of times corresponding to external image signals and thus, the gray scale is displayed. Such a sustain discharge substantially displays an image on the panel and the characteristics of the sustain discharge determines the discharge amount and brightness of the PDP.  
      Referring to  FIG. 6 , wall charges are accumulated on inner sidewalls of a discharge cell  226  due to an address discharge. Specifically, positive wall charges are accumulated on inner sidewalls of the discharge cell  226  in which a first electrode  213  is arranged and negative wall charges are accumulated on inner sidewalls of the discharge cell  226  in which a second electrode  212  is arranged. At this time, a negative potential is applied to the first electrode  213  and a positive potential is applied to the second electrode  212 .  
      Then, referring to  FIG. 7 , as a positive potential is applied to the first electrode  213  and a negative potential is applied to the second electrode  212 , a predetermined potential difference is generated, and thus, a dielectric material of a barrier rib  230  is polarized. As a result, an electric field is formed in the discharge cell  226 .  
      At this time, according to Gauss&#39; law, since an equipotential surface is formed on a surface of a conductive material when an identical potential is applied to the conductive material, an equipotential surface corresponding to the potential applied to the first electrode  213  is formed on the entire surface of the first electrode  213  and an equipotential surface corresponding to the potential applied to the second electrode  212  is formed on the entire surface of the second electrode  212 .  
      In one embodiment, the first electrode  213  is arranged to surround a first corner portion  226   b  of the discharge cell  226  and the second electrode  212  is arranged to surround a second corner portion  226   a  of the discharge cell  226 , the second corner portion  226   a  being diagonally opposite to the first corner portion  226   b . Due to the equipotential on the surface of the first electrode  213 , a strength of the electric field around the first corner portion  226   b  of the discharge cell  226  surrounded by the first electrode  213  is constant, i.e., a strength of electric field generated on surfaces which form the first corner portion  226   b  is constant. Likely, the strength of an electric field generated on surfaces which form the second corner portion  226   a  is constant.  
      In corner portions  226   c  and  226   d  other than the first corner portion  226   b  and the second corner portion  226   a  (hereinafter, referred to as discharge corner portions) of the discharge cell  226 , a strong electric field is generated in a direction from the first electrode  213  to the second electrode  212  due to the potential difference generated according to the potential applied between the first electrode  213  and the second electrode  212 .  
      The strength of the electric field at a predetermined position is decreased as the position is closer to the center of the discharge cell  226  apart from the discharge corner portions  226   c  and  226   d . This can be easily confirmed from the physical rule that the strength of an electric field is proportional to a potential difference and inversely proportional to the distance between points to which the potential is applied.  
      Thus, the wall charges accumulated on the discharge corner portions  226   c  and  226   d  due to the strong electric field generated on the discharge corner portions  226   c  and  226   d  move in the direction of the electric field. Thus, the wall charges collide with discharge gas atoms and, as illustrated in  FIG. 7 , such a collision diffuses toward the center of the discharge cell  226 , while exciting the discharge gas in the discharge cell  226  from a low energy level to a high energy level.  
      Then, while the energy level of the excited discharge gas is lowered from the high energy level to the low energy level, ultraviolet (UV) light having a predetermined wavelength is generated. The UV light excites a fluorescent layer  225  arranged in the discharge cell  226 , more specifically in a space defined by a rear barrier ribs  224  and a dielectric layer  223 . Then, while the energy level of the fluorescent layer  225  is changed from high to low, visible light is generated.  
      Unlike the conventional alternating current, triode-type, surface discharge PDP  100 , the PDP  200  comprises the discharge electrode  219  arranged in the barrier rib  230 , and the discharge diffuses from the discharge corner portions  226   c  and  226   d  to the center of the discharge cell  226 . Thus, a probability that the discharge occurs and the discharge amount are remarkably increased, compared to the conventional PDP  100  in which the discharge occurs on only a rear surface of the front substrate.  
      As described above, the discharge initiates in the discharge corner portions  226   c  and  226   d  and diffuses toward the center of the discharge cell  226  and the wall charges move between both inner sidewalls, which form each of the discharge corner portions  226   c  and  226   d  of the discharge cell  226 . Thus, a likelihood that the wall charges collide with the fluorescent layer  225  coated on the dielectric layer  223  is greatly reduced.  
      This implies that a likelihood that ion particles in the discharge cell  226  collide with the fluorescent layer  225  is greatly reduced. As a result, ion collision with the fluorescent layer  225  is inhibited and thus, ion sputtering is basically prevented.  
      When the potential difference between the first electrode  213  and the second electrode  212  becomes lower than the firing voltage after the discharge, the discharge is no longer generated, and space charges and wall charges accumulate in the discharge cell  226 . At this time, when a pulse potential of the opposite polarity is applied between the first electrode  213  and the second electrode  212 , the potential difference reaches the firing voltage with the aid of the wall charges and a discharge is generated again.  
      When the polarity of the pulse potential applied between the first electrode  213  and the second electrode  212  is repeatedly and alternately changed, the discharge is maintained. Due to the potential alternately applied between the first electrode  213  and the second electrode  212 , UV light is generated from the fluorescent layer  225  in the same number of times as the discharge occurs, thereby displaying a predetermined gray scale on the PDP. As a result, the PDP  200  can display a desired image by such a sustain discharge.  
       FIG. 9  is an exploded perspective view of a PDP  300  according to another embodiment of the present invention.  FIG. 10  is a plan view taken along line X-X of the PDP  300  illustrated in  FIG. 9 , showing the locations of first electrodes  313 , second electrodes  312 , and discharge cells  326 .  FIG. 11  is a perspective view of first electrodes  313  and second electrodes  312  of the PDP  300  illustrated in  FIG. 9 . Referring to  FIGS. 9 through 11 , the PDP  300  will be explained based on the differences from the PDP  200  illustrated in  FIG. 2 .  
      Referring to  FIGS. 9 through 11 , the PDP  300  does not comprise address electrodes  222  which are present in the PDP  200  illustrated in  FIG. 2 . The first electrodes  313  are electrically connected to first electrode connective portions  313   c  and extend in a direction in which the discharge cells  326  extend, more specifically in the x-axis direction. The second electrodes  312  are electrically connected to second electrode connective portions  312   c  and extend to cross the direction in which the first electrodes  313  extend, more specifically extend in the −y-axis direction.  
      In one embodiment, since the first electrodes  313  and the second electrodes  312  cross at the discharge cells  326 , a potential applied between the first electrodes  313  and the second electrodes  312  can be controlled to allow an address discharge to occur in one of the discharge cells  326 . Thus, a separate address electrode is not required.  
      In this embodiment, a separate process of disposing the address electrodes is not required and also a driver integrated circuit chip for controlling the potential applied to the address electrodes is not required. As a result, the production costs of the PDP  300  are greatly reduced.  
      Additionally, since the address electrodes are not formed, a dielectric layer for covering the address electrodes is not required any more in the PDP  300 , and thus, the production costs of the PDP  300  can be further reduced. As in the PDP  200  illustrated in  FIG. 2 , the first electrodes  313  may be arranged in front barrier ribs  215  such that they surround first corner portions  326   b  of the discharge cells  326 . Also, the second electrodes  312  may be arranged in the front barrier ribs  215  such that they surround second corner portions  326   a  of the discharge cells  326 .  
       FIG. 12  is an exploded perspective view of a PDP  400  according to still another embodiment of the present invention. Referring to  FIG. 12 , the PDP  400  will be explained based on the differences from the PDP  200  illustrated in  FIG. 2 . The PDP  400  differs from the PDP  200  illustrated in  FIG. 2  in the location of front barrier ribs  415 .  
      In one embodiment, the front barrier ribs  415  comprise central barrier rib portions  415   a  and side barrier rib portions  415   b  in order to prevent a misdischarge between discharge cells  426  due to the interference between first electrodes  413  and second electrodes  412  which can occur according to operation modes of the PDP  400 . Thus, the manufacturing process of the barrier ribs  415  is simplified.  
      In one embodiment, the central barrier rib portions  415   a  may be made of a material having a lower relative dielectric constant than a material of the side barrier rib portions  415   b , in order to prevent the interference between the discharge cells  426  which can occur according to the operation modes of the PDP  400 .  
       FIG. 13  is an exploded perspective view of a PDP  500  according to yet another embodiment of the present invention. The PDP  500  differs from the PDP  200  illustrated in  FIG. 2  in that integrated barrier ribs  530  in the PDP  500  replace the front barrier ribs  215  and the rear barrier ribs  224  in the PDP  200 .  
      In one embodiment, the integration of the front barrier ribs  215  and the rear barrier ribs  224  into the integrated barrier ribs  530  means that front barrier ribs  215  and the rear barrier ribs  224  are joined and cannot be separated without breaking, but does not mean that the barrier ribs  530  are produced in one process. The basic characteristics of the integrated barrier ribs  530  in the PDP  500  are the same as in the PDP  200 , for example, the barrier ribs  530  define discharge cells  526  and resist a pressure applied by the discharge gas in a vacuum state.  
      Referring to the enlarged view shown in  FIG. 13 , the manufacturing process of an integrated barrier rib  530  will be now briefly explained.  
      First, a rear portion  530   a  of the barrier rib  530  is formed on a front surface  221   a  of a rear substrate  222 . Then, a space defined by the rear portion  530   a  is filled with a paste comprising a fluorescent material and the paste is dried and baked. Next, a first barrier rib layer  530   ba  is formed on the rear portion  530   a  of the integrated barrier rib  530 , and a first electrode  213  and a second electrode  212  are formed on the first barrier rib layer  530   ba . Then, a second barrier rib layer  530   bb  is formed to cover the first electrode  213  and the second electrode  212  to obtain a front portion  530   b  of the barrier rib  530 . The rear portion  530   a , the first barrier rib layer  530   ba , and the second barrier rib layer  530   bb  may each comprise more than two layers, if necessary, to increase their thicknesses.  
      After forming the integrated barrier rib  530 , protective layers  216  are formed on at least sidewalls  530   g  of the front portion  530   a  of the integrated barrier rib  530 , using deposition. In one embodiment, during the deposition of the protective layers  216 , rear protective layers (not shown) may also be formed on front surfaces  225   a  of fluorescent layers  225 . The function of the protective layers  216  is as described above.  
      In one embodiment, during the deposition of the protective layers  216 , a protective layer may be further formed on a front surface  530   h  of the integrated barrier rib  530 . The protective layer formed on the front surface  530   h  does not have a great adverse effect on the operation of the PDP  500 .  
      The PDP according to embodiments of the present invention has the following effects.  
      First, the PDP has a structure in which discharge electrodes are arranged in barrier ribs surrounding discharge cells, unlike a conventional PDP in which pairs of sustain electrodes are arranged in a front panel. Thus, there is no need for a dielectric layer or a protective layer, etc., on the front panel through which visible light is transmitted. As a result, the PDP allows the visible light generated by fluorescent layers in the discharge cells to pass directly through a front substrate, thereby greatly increasing light transmittance.  
      Second, in the conventional PDP, the sustain electrodes which generate the discharge are arranged on the rear surface of the front substrate, and in order to allow the visible light generated by the fluorescent layers in the discharge cells to be transmitted through the front substrate, the majority of the sustain electrodes must be formed of ITO, which is very expensive and highly resistive. Thus, the driving voltage is increased and the production costs of the conventional PDP are high. Further, since the high resistance of the ITO electrodes causes a voltage drop, images cannot be uniformly realized when the conventional PDP is large. However, in the PDP according to one embodiment of the present invention, the discharge electrodes are arranged in the barrier ribs, and thus, the discharge electrodes can be formed of a highly conductive, inexpensive material.  
      Third, in the conventional PDP, the sustain electrodes are formed on the rear surface of the front substrate, and the discharge occurs behind the protective layer in the discharge cells and diffuses within the discharge cells. Thus, the luminous efficiency of the conventional PDP is reduced. When the conventional PDP is used for a long time, a charged discharge gas induces ion sputtering of the fluorescent material due to the electric field, thereby resulting in permanent after-images. However, in the PDP according to one embodiment the present invention, the discharge occurs in discharge corner portions of the discharge cells and diffuses to concentrate on the centers of the discharge cells, increasing the discharge efficiency. The wall charges move between both inner sidewalls which form each of the discharge corner portions of the discharge cells, and thus, the amount of ion particles that collide with fluorescent layers is remarkably reduced. As a result, ion sputtering of the fluorescent material is prevented, thereby extending the lifetime of the PDP and preventing the permanent after-images which lower the image quality.  
      Fourth, in the PDP according to one embodiment of the present invention, first electrodes and second electrodes are arranged in the barrier ribs and the discharge stereoscopically occurs along the discharge corner portions of the discharge cells, and thus a discharge space is enlarged, thereby increasing the discharge efficiency. As a result, a driving voltage of the PDP can be reduced and a low voltage driving integrated circuit can be used, thereby reducing the production costs of the PDP.  
      While the above description has pointed out novel features of the invention as applied to various embodiments, the skilled person will understand that various omissions, substitutions, and changes in the form and details of the device or process illustrated may be made without departing from the scope of the invention. Therefore, the scope of the invention is defined by the appended claims rather than by the foregoing description. All variations coming within the meaning and range of equivalency of the claims are embraced within their scope.