Abstract:
The present invention relates to a plasma display panel and more specifically to a plasma display panel in which metal and auxiliary metal electrodes are formed such that brightness and efficiency are improved.  
     A plasma display panel according to the present invention comprises: transparent ITO electrodes which are spaced in parallel to each other at a predetermined distance within a discharge cell; metal electrodes which are formed in parallel to said transparent ITO electrodes and formed on verge of said transparent ITO electrodes, respectively; and auxiliary metal electrodes which are formed on said transparent ITO electrodes so that are positioned in the direction of sides of said transparent ITO electrodes which are opposite to each other, respectively.

Description:
TECHNICAL FIELD  
         [0001]    The present invention relates to a plasma display panel and more specifically to a plasma display panel in which metal and auxiliary metal electrodes are formed such that brightness and efficiency are improved.  
         BACKGROUND OF THE INVENTION  
         [0002]    [0002]FIG. 1 is a perspective view illustrating a discharge cell of a general AC plasma display panel arranged in matrix shape.  
           [0003]    As shown in FIG. 1, a conventional PDP comprises a front substrate  10  and rear substrate  12 . A pair of sustain electrode  14 ,  16 , upper dielectric layer  18  and protective layer  20  are gradually formed on the front substrate  10 , and address electrodes  22 , lower dielectric layer  24  and barrier ribs  26  and phosphor layer  28  are gradually formed on the rear substrate  12 . The front substrate  10  and the rear substrate  12  are spaced in parallel to each other at a predetermined distance by barrier ribs  26 .  
           [0004]    Wall charges occurred upon the plasma discharge is accumulated on the upper dielectric layer  18  and the lower dielectric layer  24 . The protection layer  20  serves to prevent damage of the upper dielectric layer  18  due to sputtering generated upon the plasma discharge and to increase emission efficiency of secondary electrons. The protection layer  20  is usually formed using magnesium oxide (MgO).  
           [0005]    The address electrodes  22  are formed in the direction intersecting a pair of sustain electrodes  14 ,  16 . A data signal is supplied for the address electrodes  22  to select a cell that is displayed.  
           [0006]    The barrier ribs  26  are formed in parallel to the address electrode  22  and serves to prevent ultraviolet rays and a visible ray generated due to the discharge from leaking toward neighboring discharge cells. The barrier ribs  26  may be existed or not a boundary line of sub-pixel.  
           [0007]    The phosphor layer  28  is excited by ultraviolet rays generated upon the plasma discharge to generate a visible ray of one of red, green and blue. Inert mixed gases such as He+Xe, Ne+Xe and He+Ne+Xe for discharge are inserted into a discharge space of the discharge cell formed between the upper/lower substrates  10 ,  12 .  
           [0008]    A pair of sustain electrode  14 ,  16  comprises scan electrodes  14  and sustain electrodes  16 . A scan signal for scanning of the panel is supplied for scan electrodes  14  and a sustain signal for maintaining discharge of a selected cell is supplied for sustain electrodes.  
           [0009]    A pair of sustain electrode  14 ,  16  comprises transparent ITO electrodes  14 A,  16 A, which are stripe pattern, are made of transparent material in order to transmit a visible ray and have a wide width relatively, and metal electrodes  14 B,  16 B, which compensate a resistance of transparent ITO electrodes  14 A,  16 A and have a narrow width relatively. Each of the transparent ITO electrodes of a pair of sustain electrodes  14 ,  16  is opposite to each other at a predetermined distance. Further, metal electrodes  14 B,  16 B are formed in parallel to the transparent ITO electrodes  14 A,  16 A and formed on a verge of the transparent ITO electrodes  14 A,  16 A, respectively. Namely, metal electrodes  14 B,  16 B are formed on outside verge of the transparent ITO electrodes  14 A,  16 A.  
           [0010]    A PDP cell of this structure sustains a discharge according to surface discharge between a pair of sustain electrodes  14 ,  16  after being selected by opposite discharge between the address electrode  22  and the scan electrode  14 . In the PDP cell, a visible ray is emitted to an outside of cell as radiating phosphors  28  by ultraviolet rays which are generated while the sustain discharge occurs. As a result, the PDP having cells displays an image. In this case, the PDP realizes a gray scale by controlling the discharge sustaining period, i.e. the number of sustain discharge according to a video data.  
           [0011]    In the conventional PDP, Xe inert gas excites phosphors  28  using a vacuum ultraviolet generated by changing from excited state to ground state according to gas discharge. Therefore, as a content of Xe is much, a quantity of vacuum ultraviolet rays generated upon the gas discharge and the efficiency of the PDP increase. However, the increase of Xe is caused by rising discharge starting voltage and discharge sustaining voltage between sustain electrodes.  
           [0012]    Furthermore, in the conventional PDP, the discharge starting voltage and the discharge sustaining voltage is risen because the metal electrodes  14 B,  16 B are formed on the outside verge of the transparent ITO electrodes  14 A,  16 A, respectively. Also, the brightness and efficiency of the conventional PDP are decreased.  
           [0013]    That is, the conventional PDP structure has a difficulty in increasing brightness and efficiency without any problem such as the structure of electrodes within the discharge cell.  
         SUMMARY OF THE INVENTION  
         [0014]    Accordingly, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a plasma display panel for increasing brightness and efficiency.  
           [0015]    A plasma display panel comprises: transparent ITO electrodes which are spaced in parallel to each other at a predetermined distance within a discharge cell; metal electrodes which are formed in parallel to said transparent ITO electrodes and formed on verge of said transparent ITO electrodes, respectively; and auxiliary metal electrodes which are formed on said transparent ITO electrodes so that are positioned in the direction of sides of said transparent ITO electrodes which are opposite to each other, respectively.  
           [0016]    Further a plasma display panel comprises: transparent ITO electrodes which are spaced in parallel to each other at a predetermined distance within a discharge cell; metal electrodes which are formed on said transparent ITO electrodes and in parallel to said transparent ITO electrodes so that are positioned in the direction of sides of said transparent ITO electrodes which are opposite to each other, respectively; and auxiliary metal electrodes which are formed on verge of said transparent ITO electrodes, respectively. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    [0017]FIG. 1 is a perspective view illustrating a discharge cell of a plasma display panel of the prior art.  
         [0018]    [0018]FIG. 2 is a plane view illustrating a pair of sustain electrodes shown in FIG. 1.  
         [0019]    [0019]FIG. 3 is a perspective view illustrating a discharge cell of a plasma display panel according to a first embodiment of the present invention.  
         [0020]    [0020]FIG. 4 is a plane view illustrating a pair of sustain electrodes according to the first embodiment of the present invention shown in FIG. 3.  
         [0021]    [0021]FIG. 5 is a cross-sectional view of a pair of sustain electrodes of FIG. 4 taken along a line A-A′.  
         [0022]    [0022]FIG. 6 is a current density of a pair of sustain electrodes during discharge shown in FIG. 4.  
         [0023]    [0023]FIG. 7 is a discharge state of a pair of sustain electrodes shown in FIG. 4 while discharge generates.  
         [0024]    [0024]FIG. 8 is a graph showing comparison of brightness between the first embodiment of the present invention and the prior art with respect to discharge voltage.  
         [0025]    [0025]FIG. 9 is a graph showing comparison of efficiency between the first embodiment of the present invention and the prior art with respect to discharge voltage.  
         [0026]    [0026]FIG. 10 is a plane view illustrating a pair of sustain electrodes according to a modification of the first embodiment.  
         [0027]    [0027]FIG. 11 is a cross-sectional view of a pair of sustain electrodes of FIG. 10 taken along a line B-B′.  
         [0028]    [0028]FIG. 12 is a plane view illustrating a pair of sustain electrodes according to another modification of the first embodiment.  
         [0029]    [0029]FIG. 13 is a perspective view illustrating a discharge cell of a plasma display panel according to the second embodiment of the present invention.  
         [0030]    [0030]FIG. 14 is a plane view illustrating a pair of sustain electrodes shown in FIG. 13.  
         [0031]    [0031]FIG. 15 is a cross-sectional view of a pair of sustain electrodes of FIG. 14 taken along a line A-A′.  
         [0032]    [0032]FIG. 16 is a graph showing comparison of brightness between the second embodiment of the present invention and the prior art with respect to discharge voltage.  
         [0033]    [0033]FIG. 17 is a graph showing comparison of efficiency between the second embodiment of the present invention and the prior art with respect to discharge voltage.  
         [0034]    [0034]FIG. 18 is a plane view illustrating a pair of sustain electrodes according to a modification of the second embodiment.  
         [0035]    [0035]FIG. 19 is a plane view illustrating a pair of sustain electrodes according to another modification of the second embodiment. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0036]    Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.  
         [0037]    The First Embodiment  
         [0038]    [0038]FIG. 3 is a perspective view illustrating a discharge cell of a plasma display panel according to a first embodiment of the present invention, FIG. 4 is a plane view illustrating a pair of sustain electrodes according to the first embodiment of the present invention shown in FIG. 3, and FIG. 5 is a cross-sectional view of a pair of sustain electrodes of FIG. 4 taken along a line A-A′.  
         [0039]    As shown in FIG. 3, a plasma display panel according to the first embodiment of the present invention has a front substrate  110  and rear substrate  112 . A pair of sustain electrodes  114 ,  116 , upper dielectric layer  118  and protective layer  120  are gradually formed on the front substrate  110 , and address electrodes  122 , lower dielectric layer  124  and barrier ribs  126  and phosphor layer  28  are gradually formed on the rear substrate  112 . The front substrate  110  and the rear substrate  112  are spaced in parallel to each other at a predetermined distance by barrier ribs  126 .  
         [0040]    According to the first embodiment of the present invention, the sustain electrodes  114 ,  116  are consisted of the transparent ITO electrodes  114 A,  116 A and the metal electrodes  114 B,  116 B and the auxiliary metal electrodes  114 C,  116 C on the transparent ITO electrodes  114 A,  116 A.  
         [0041]    Each of the transparent ITO electrodes  114 A,  116 A of a pair of sustain electrodes  114 ,  116  are opposite to each other at a predetermined distance.  
         [0042]    The transparent ITO electrodes  114 A,  116 A are made of transparent material in order to transmit a visible ray, and have a stripe pattern of a wide width relatively.  
         [0043]    The metal electrodes  114 B,  116 B are formed on a verge of the transparent ITO  114 A,  116 A and have a stripe pattern of a narrow width relatively, respectively. The metal electrodes  114 B,  116 B and the auxiliary metal electrodes  114 C,  116 C made of material having a good conductivity in order to compensate a conductivity of transparent ITO electrodes  114 A,  116 A.  
         [0044]    As shown in FIG. 4 and FIG. 5, each of the auxiliary metal electrodes  114 A,  116 A is formed in stripe shape of smaller. size than a width of the transparent ITO electrodes  114 A,  116 A and is formed so that are positioned in the direction of sides of the transparent ITO electrodes  114 A,  116 A which are opposite to each other. Preferably, each of the auxiliary metal electrodes  114 C,  116 C is a quadrangle and is formed in parallel and in equidistance with the transparent ITO electrodes  114 A,  116 A.  
         [0045]    A discharge voltage supplied from the metal electrodes  114 B,  116 B via the transparent ITO electrodes  114 A,  116 A is applied to each of the auxiliary metal electrodes  114 C,  116 C. In this result, each of the auxiliary metal electrodes  114 C,  116 C induces a strong electric field in the central portion of discharge cell and the discharge starting voltage and the discharge sustaining voltage are decreased.  
         [0046]    A PDP cell of this structure is sustained a discharge according to surface discharge between a pair of sustain electrodes  114 ,  116  after being selected by opposite discharge between the address electrode  122  and the scan electrode  114 . As shown in FIG. 6, at this time of the surface discharge, a current density strongly generates between the auxiliary metal electrodes  114 C,  116 C of the central portion of the discharge cell, and then expands in the direction of the metal electrodes  114 B,  116 B situated the outside of the discharge cell, gradually.  
         [0047]    Further, as shown in FIG. 7, at this time of the surface discharge, a strong discharge generates between the auxiliary metal electrodes  114 C,  116 C of the central portion of the discharge cell, and then expands in the direction of the metal electrodes  114 B,  116 B situated the outside of the discharge cell, gradually. And, in the PDP cell, a visible ray is emitted to the outside cell as radiating phosphors  128  by generated ultraviolet rays when the sustain discharge occurs. In result, the PDP having cells displays an image. In this case, the PDP implements a gray scale depending on the number of discharge according to a video data.  
         [0048]    In the conventional PDP, Xe inert gas excites phosphors  28  using a vacuum ultraviolet generated upon changing from excited state to ground state. Therefore, as a content of Xe is much, a quantity of vacuum ultraviolet rays generated upon the gas discharge and the efficiency of the PDP increase. However, the increase of Xe is caused by rising discharge starting voltage and discharge sustaining voltage between sustain electrodes.  
         [0049]    However, in the PDP according to the first embodiment of the present invention, the discharge starting voltage and discharge sustaining voltage are decreased and the brightness and efficiency are increased at this time of the discharge, although the contents of Xe inert gas increases.  
         [0050]    In the concrete, since the distance between the auxiliary metal electrodes  114 C,  116 C is near, the strong electric field generates at the central portion of the discharge cell, at this time of the discharge. And, the discharge starting voltage and discharge sustaining voltage are decreased by the strong electric field generated at the central portion of the discharge cell. Therefore, as shown in FIG. 8 and FIG. 9, the brightness of the PDP according to the first embodiment of the present invention is improved the maximum 57% than the conventional PDP at the discharge voltage, 260V, and the efficiency of the PDP according to the first embodiment of the present invention is improved approximately 39% than the conventional PDP at the discharge voltage, 200V.  
         [0051]    [0051]FIG. 10 is a plane view illustrating a pair of sustain electrodes according to a modification of the first embodiment.  
         [0052]    The description of the same elements with the first embodiment of the present invention shown in FIG. 3 is omitted.  
         [0053]    According to the modification of the first embodiment of the present invention, the sustain electrodes  214 ,  216  are consisted of the transparent ITO electrodes  214 A,  216 A and the metal electrodes  214 B,  216 B and the auxiliary metal electrodes  214 C,  216 C on the transparent ITO electrodes  214 A,  216 A.  
         [0054]    Each of the transparent ITO electrodes  214 A,  216 A of a pair of sustain electrodes  214 ,  216  are opposite to each other at a predetermined distance.  
         [0055]    The transparent ITO electrodes  214 A,  216 A are made of transparent material in order to transmit a visible ray and have a stripe pattern of a wide width relatively.  
         [0056]    The metal electrodes  214 B,  216 B are formed on a verge of the transparent ITO  214 A,  216 A and have a stripe pattern of a narrow width relatively, respectively. The metal electrodes  214 B,  216 B and the auxiliary metal electrodes  214 C,  216 C are made of material having a good conductivity in order to compensate a conductivity of transparent ITO electrodes  214 A,  216 A.  
         [0057]    As shown in FIG. 10 and FIG. 11, each of the auxiliary metal electrodes  214 C,  216 C is formed in stripe shape of smaller size than a width of the transparent ITO electrodes  214 A,  216 A and is formed so that are positioned in the direction of sides of the transparent ITO electrodes  214 A,  216 A which are opposite to each other. Preferably, each of the auxiliary metal electrodes  214 C,  216 C is a quadrangle and is formed in parallel and in equidistance with the transparent ITO electrodes  214 A,  216 A. The auxiliary metal electrodes  214 C,  216 C are formed on the opposite sides of the transparent ITO electrodes  214 A,  216 A in single and double line and are formed in parallel and in equidistance each other.  
         [0058]    A discharge voltage supplied from the metal electrodes  214 B,  216 B via the transparent ITO electrodes  214 A,  216 A is applied to each of the auxiliary metal electrodes  214 C,  216 C. In this result, each of the auxiliary metal electrodes  214 C,  216 C induces a strong electric field in the central portion of discharge cell and the discharge starting voltage and the discharge sustaining voltage are decreased.  
         [0059]    In this time, the appearance of the current density and discharge is similar to that shown in FIG. 6 and FIG. 7 and the characteristic of the brightness and efficiency are similar to that shown in FIG. 8 and FIG. 9.  
         [0060]    [0060]FIG. 12 is a plane view illustrating a pair of sustain electrodes according to another modification of the first embodiment.  
         [0061]    The description of the same elements with the first embodiment of the present invention shown in FIG. 3 is omitted.  
         [0062]    According to another transformation of the first embodiment of the present invention, the sustain electrodes  314 ,  316  are consisted of the transparent ITO electrodes  314 A,  316 A and the metal electrodes  314 B,  316 B and the auxiliary metal electrodes  314 C,  316 C on the transparent ITO electrodes  314 A,  316 A.  
         [0063]    Each of the transparent ITO electrodes  314 A,  316 A of a pair of sustain electrodes  314 ,  316  are opposite to each other at a predetermined distance.  
         [0064]    The transparent ITO electrodes  314 A,  316 A are made of transparent material in order to transmit a visible ray and have a stripe pattern of a wide width relatively.  
         [0065]    The metal electrodes  314 B,  316 B are formed on a verge of the transparent ITO  314 A,  316 A and have a stripe pattern of a narrow width relatively, respectively. The metal electrodes  314 B,  316 B and the auxiliary metal electrodes  314 C,  316 C made of material having a good conductivity in order to compensate a conductivity of transparent ITO electrodes  314 A,  316 A.  
         [0066]    As shown in FIG. 12, each of the auxiliary metal electrodes  314 A,  316 A is formed in stripe shape of smaller size than a width of the transparent ITO electrodes  314 A,  316 A and is formed so that are positioned in the direction of sides of the transparent ITO electrodes  314 A,  316 A which are opposite to each other. Preferably, each of the auxiliary metal electrodes  314 C,  316 C is a quadrangle and is formed in parallel and in equidistance with the transparent ITO electrodes  314 A,  316 A. Furthermore, each of the auxiliary metal electrodes  314 C,  316 C consists of three electrodes made of triangular shape.  
         [0067]    A discharge voltage supplied from the metal electrodes  314 B,  316 B via the transparent ITO electrodes  314 A,  316 A is applied to each of the auxiliary metal electrodes  314 C,  316 C. In this result, each of the auxiliary metal electrodes  314 C,  316 C induces a strong electric field in the central portion of discharge cell and the discharge starting voltage and the discharge sustaining voltage are decreased.  
         [0068]    In this time, the appearance of the current density and discharge is similar to that shown in FIG. 6 and FIG. 7 and the characteristic of the brightness and efficiency are similar to that shown in FIG. 8 and FIG. 9.  
         [0069]    The Second Embodiment  
         [0070]    [0070]FIG. 13 is a perspective view illustrating a discharge cell of a plasma display panel according to the second embodiment of the present invention, FIG. 14 is a plane view illustrating a pair of sustain electrodes shown in FIG. 13 and FIG. 15 is a cross-sectional view of a pair of sustain electrodes of FIG. 14 taken along a line A-A′.  
         [0071]    The description of the same elements with the first embodiment of the present invention shown in FIG. 3 is omitted.  
         [0072]    According to the second embodiment of the present invention, the sustain electrodes  414 ,  416  are consisted of the transparent ITO electrodes  414 A,  416 A and the metal electrodes  414 B,  416 B and the auxiliary metal electrodes  414 C,  416 C on the transparent ITO electrodes  414 A,  416 A.  
         [0073]    Each of the transparent ITO electrodes  414 A,  416 A of a pair of sustain electrodes  414 ,  416  are opposite to each other at a predetermined distance.  
         [0074]    Each of the metal electrodes  414 B,  416 B is formed on the transparent ITO electrodes  414 A,  416 A between a central portion of the transparent ITO electrodes  414 A,  416 A and a central portion of the discharge cell.  
         [0075]    That is, each of the metal electrodes  414 B,  416 B is formed on the transparent ITO electrodes  414 A,  416 A so that is positioned in the direction of sides of the transparent ITO electrodes  414 A,  416 A which are opposite to each other.  
         [0076]    Preferably, the position of each of the metal electrodes  414 B,  416 B satisfies the following the equation 1. 
           D&lt;H /4  [Equation.1] 
         [0077]    Wherein H represents a length of discharge cell, D represents a distance between a central portion of the metal electrodes  414 B,  416 B and a central portion of the discharge cell.  
         [0078]    Each of the metal electrodes  414 B,  416 B induces a strong electric field in the central portion of discharge cell and the discharge starting voltage and the discharge sustaining voltage are decreased.  
         [0079]    As shown in FIG. 14, each of the auxiliary metal electrodes  414 C,  416 C is formed in stripe shape of smaller size than a width of the transparent ITO electrodes  414 A,  416 A and is formed so that are positioned in the direction of sides of the transparent ITO electrodes  414 A,  416 A which are opposite to each other. Preferably, each of the auxiliary metal electrodes  414 C,  416 C is a quadrangle.  
         [0080]    A surface discharge is occurred between the metal electrodes  414 B,  416 B by applied voltage, and then the discharge is expanded in the direction of the outside sides of the discharge cell by the auxiliary metal electrodes  414 C,  416 C.  
         [0081]    In the PDP according to the second embodiment of the present invention, the discharge starting voltage and discharge sustaining voltage are decreased and the brightness and efficiency are increased at this time of the discharge, although the contents of Xe inert gas increases. In the concrete, since the distance between the metal electrodes  414 B,  416 B is near, the strong electric field generates at the central portion of the discharge cell, at this time of the discharge, and then the discharge is expanded in the direction of the verge of the discharge cell. In this result, the discharge starting voltage and discharge sustaining voltage are decreased by the generated strong electric field at the central portion of the discharge cell and the brightness and efficiency are increased. Furthermore, since the discharge starting voltage and the discharge delay time are decreased, the stability of the discharge is improved.  
         [0082]    The brightness and efficiency of the second embodiment according to the present invention and the conventional PDP show in FIG. 16 and FIG. 17. As shown in FIG. 16, the brightness of the PDP according to the second embodiment of the present invention is improved the approximately 50% to 70% than the conventional PDP at the same discharge voltage. As shown in FIG. 16, the efficiency of the PDP according to the second embodiment of the present invention is improved approximately 40% to 50% than the conventional PDP at the same discharge voltage.  
         [0083]    [0083]FIG. 18 is a plane view illustrating a pair of sustain electrodes according to a modification of the second embodiment.  
         [0084]    According to a modification of the second embodiment of the present invention, the sustain electrodes  514 ,  516  are consisted of the transparent ITO electrodes  514 A,  516 A and the metal electrodes  514 B,  516 B and the auxiliary metal electrodes  514 C,  516 C on the transparent ITO electrodes  514 A,  516 A.  
         [0085]    Each of the transparent ITO electrodes  514 A,  516 A of a pair of sustain electrodes  514 ,  516  are opposite to each other at a predetermined distance.  
         [0086]    The transparent ITO electrodes  514 A,  516 A are made of transparent material in order to transmit a visible ray and have a stripe pattern of a wide width relatively.  
         [0087]    Each of the metal electrodes  514 B,  516 B is formed on the transparent ITO electrodes  514 A,  516 A between a central portion of the transparent ITO electrodes  514 A,  516 A and a central portion of the discharge cell.  
         [0088]    That is, each of the metal electrodes  514 B,  516 B is formed on the transparent ITO electrodes  514 A,  516 A so that is positioned in the direction of sides of the transparent ITO electrodes  514 A,  516 A which are opposite to each other.  
         [0089]    Each of the metal electrodes  514 B,  516 B induces a strong electric field in the central portion of discharge cell and the discharge starting voltage and the discharge sustaining voltage are decreased.  
         [0090]    As shown in FIG. 18, the auxiliary metal electrodes  514 C,  516 C are formed in stripe shape of smaller size than a width of the transparent ITO electrodes  514 A,  516 A between verge of the transparent ITO electrodes  514 A,  516 A and the metal electrodes  514 B,  516 B, respectively. Preferably, each of the auxiliary metal electrodes  514 C,  516 C is a quadrangle and is formed in single and double line and in parallel and in equidistance each other.  
         [0091]    The surface discharge is occurred between the metal electrodes  514 B,  516 B via applied voltage, and then the discharge is expanded in the direction of the outside sides of the discharge cell by the auxiliary metal electrodes  514 C,  516 C.  
         [0092]    [0092]FIG. 19 is a plane view illustrating a pair of sustain electrodes according to another modification of the second embodiment.  
         [0093]    According to another modification of the second embodiment of the present invention, the sustain electrodes  614 ,  616  are consisted of the transparent ITO electrodes  614 A,  616 A and the metal electrodes  614 B,  616 B and the auxiliary metal electrodes  614 C,  616 C on the transparent ITO electrodes  614 A,  616 A.  
         [0094]    Each of the transparent ITO electrodes  614 A,  616 A of a pair of sustain electrodes  614 ,  616  are opposite to each other at a predetermined distance.  
         [0095]    The transparent ITO electrodes  614 A,  616 A are made of transparent material in order to transmit a visible ray and have a stripe pattern of a wide width relatively.  
         [0096]    Each of the metal electrodes  614 B,  616 B is formed on the transparent ITO electrodes  614 A,  616 A between a central portion of the transparent ITO electrodes  614 A,  616 A and a central portion of the discharge cell.  
         [0097]    That is, each of the metal electrodes  614 B,  616 B is formed on the transparent ITO electrodes  614 A,  616 A so that is positioned in the direction of sides of the transparent ITO electrodes  614 A,  616 A which are opposite to each other.  
         [0098]    Each of the metal electrodes  614 B,  616 B induces a strong electric field in the central portion of discharge cell and the discharge starting voltage and the discharge sustaining voltage are decreased.  
         [0099]    As shown in FIG. 19, the auxiliary metal electrodes  614 C,  616 C are formed in stripe shape of smaller size than a width of the transparent ITO electrodes  614 A,  616 A between verge of the transparent ITO electrodes  614 A,  616 A and the metal electrodes  614 B,  616 B, respectively. Preferably, each of the auxiliary metal electrodes  614 C,  616 C is a quadrangle and consists of three electrodes made of triangular shape.  
         [0100]    The surface discharge is occurred between the metal electrodes  614 B,  616 B via applied voltage, and then the discharge is expanded in the direction of the outside sides of the discharge cell by the auxiliary metal electrodes  614 C,  616 C.  
       INDUSTRIAL APPLICABILITY  
       [0101]    In a plasma display panel according to a first embodiment of the present invention, an auxiliary metal electrode induces a strong electric field in the central portion of discharge cell and the discharge starting voltage and the discharge sustaining voltage are decreased. Therefore, the present invention has an effect that it can increase the brightness and efficiency at the same discharge voltage.  
         [0102]    In a plasma display panel according to a second embodiment of the present invention, since a distance between metal electrodes is near, the strong electric field generates at the central portion of the discharge cell and the discharge is expanded in the direction of the verge of the discharge cell by an auxiliary metal electrode. Therefore, the discharge starting voltage and discharge sustaining voltage are decreased and the brightness and efficiency are increased at the same discharge voltage. Furthermore, as the discharge starting voltage and the discharge delay time are decreased, the stability of the discharge is improved.