Patent Publication Number: US-6906689-B2

Title: Plasma display panel and driving method thereof

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a plasma display panel, and more particularly to a plasma display panel that is adaptive for improving discharge efficiency. 
     2. Description of the Related Art 
     Generally, a plasma display panel (PDP) is a display device utilizing a visible light emitted from a Phosphor layer when an ultraviolet ray generated by a gas discharge excites the Phosphor layer. The PDP has an advantage in that it has a thinner thickness and a lighter weight in comparison to the existent cathode ray tube (CRT) and is capable of realizing a high resolution and a large-scale screen. The PDP includes of a plurality of discharge cells arranged in a matrix pattern, each of which makes one pixel of a field. 
       FIG. 1  is a perspective view showing a discharge cell structure of a conventional three-electrode, alternating current (AC) surface-discharge PDP. 
     Referring to  FIG. 1 , a discharge cell of the conventional three-electrode, AC surface-discharge PDP includes the first electrode  12 Y and the second electrode  12 Z provided on an upper substrate  10 , and an address electrode  20 X provided on a lower substrate  18 . 
     Each of the first electrode  12 Y and the second electrode  12 Z is a transparent electrode made from indium-tin-oxide (ITO). Since the ITO has a high resistance value, the rear sides of the first and second electrodes  12 Y and  12 Z are provided with bus electrodes  13 Y and  13 Z made from a metal, respectively. The bus electrodes  13 Y and  13 Z supply a driving signal from the exterior to the first and second electrodes  12 Y and  12 Z, thereby applying a uniform voltage to each discharge cell. 
     On the upper substrate  10  provided with the first electrode  12 Y and the second electrode  12 Z in parallel, an upper dielectric layer  14  and a protective layer  16  are disposed. Wall charges generated upon plasma discharge are accumulated into the upper dielectric layer  14 . The protective layer  16  prevents a damage of the upper dielectric layer  14  caused by a sputtering during the plasma discharge and improves the emission efficiency of secondary electrons. This protective film  16  is usually made from magnesium oxide (MgO). 
     A lower dielectric layer  22  and barrier ribs  24  are formed on the lower substrate  18  provided with the address electrode  20 X. The surfaces of the lower dielectric layer  22  and the barrier ribs  24  are coated with a Phosphor layer  26 . The address electrode  20 X is formed in a direction crossing the first electrode  12 Y and the second electrode  12 Z. 
     The barrier rib  24  is formed in parallel to the address electrode  20 X to prevent an ultraviolet ray and a visible light generated by a discharge from being leaked to the adjacent discharge cells. The Phosphor layer  26  is excited by an ultraviolet ray generated during the plasma discharge to generate any one of red, green and blue visible light rays. An inactive gas for a gas discharge is injected into a discharge space defined between the upper and lower substrate  10  and  18  and the barrier rib  24 . 
     Such a PDP drives one frame, which is divided into various sub-fields having a different discharge frequency, so as to express gray levels of a picture. Each sub-field is again divided into an initialization period for uniformly causing a discharge, an address period for selecting the discharge cell and a sustain period for realizing the gray levels depending on the discharge frequency. For instance, when it is intended to display a picture of 256 gray levels, a frame interval equal to {fraction (1/60)} second (i.e. 16.67 msec) is divided into 8 sub-fields SF 1  to SF 8  as shown in FIG.  2 . Each of the 8 sub-fields SF 1  to SF 8  is divided into an address period and a sustain period. Herein, the initialization period and the address period of each sub-field are equal at every sub-field, whereas the sustain period are increased at a ratio of 2 n  (wherein n=0, 1, 2, 3, 4, 5, 6 and 7) at each sub-field. 
       FIG. 3  is a waveform diagram of a driving signal applied to each electrode of the conventional PDP. 
     Referring to  FIG. 3 , one sub-field is divided into an initialization period for initializing the entire field, an address period for writing a data while scanning the entire field on a line-sequence basis, and a sustain period for sustaining an emission state of the cells into which a data is written. 
     The first, in the initialization period, an initialization waveform RP is applied to the first electrodes Y. If so, an initialization discharge is generated between the first electrodes Y and the second electrodes Z to initialize the discharge cells. At this time, a misfiring prevention pulse is applied to the address electrodes X. 
     In the address period, a scan pulse −Vs is sequentially applied to the first electrodes Y. A data pulse Vd synchronized with the scan pulse −Vs is applied to the address electrodes X. At this time, an address discharge is generated at the discharge cells to which the data pulse Vd and the scan pulse −Vs are applied. 
     In the sustain period, the first and second sustain pulses SUSPy and SUSPz are applied to the first and second electrodes Y and Z. At this time, a sustain discharge is generated at the discharge cells which have generated the address discharge, to thereby display a desired picture on the PDP. 
       FIG. 4  is a detailed view showing a structure of the first and second electrodes provided on the upper substrate of the PDP. 
     Referring to  FIG. 4 , each of the first and second electrodes  12 Y and  12 Z provided on the upper substrate  10  of the PDP have a width of about 390 μm. The first and second electrodes  12 Y and  12 Z are formed on the upper substrate  10  at a space of about 60 μm. Further, a distance extending from the first and second electrodes  12 Y and  12 Z until a boundary portion of the discharge cell is set to be about 210 μm. In other words, the conventional first and second electrodes  12 Y and  12 Z are provided at the center of the discharge cell. Thus, a sustain discharge generated between the first electrode  12 Y and the second electrode  12 Z concentrates on the center of the discharge cell. If the sustain discharge concentrates on the center of the discharge cell, then a utility of a discharge space is deteriorated and hence a discharge efficiency is deteriorated. 
     In order to solve this problem, a space between the first electrode  12 Y and the second electrode  12 Z may be set widely. In other words, if a space between the first electrode  12 Y and the second electrode  12 Z is widened, then a discharge path can be lengthened to improve discharge efficiency. 
     However, a widened space between the first electrode  12 Y and the second electrode  12 Z causes a rise of a firing voltage and a discharge sustaining voltage to thereby increase total driving voltage. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a plasma display panel and a driving method that is adaptive for improving discharge efficiency. 
     In order to achieve these and other objects of the invention, a plasma display panel according to one aspect of the present invention includes a plurality of the first and second electrodes provided at the rear side of an upper substrate; a dielectric layer provided at the rear side of the upper substrate in such a manner to cover the upper substrate and the first and second electrodes; and a plurality of the first and second auxiliary electrodes provided in parallel to the first and second electrodes within the dielectric layer. 
     In the plasma display panel, the first and second auxiliary electrodes are provided at the edge of the discharge cell. 
     The first auxiliary electrode overlaps with the first electrode and the second auxiliary electrode overlaps with the second electrode. 
     Each of the first and second auxiliary electrodes has a narrower width than each of the first and second electrodes. 
     The widths of the first and second auxiliary electrodes are set to 10 μm to 80 μm. The widths of the first and second auxiliary electrodes are preferably set to 40 μm. 
     The first auxiliary electrode is spaced at 10 μm to 40 μm from the first electrode and the second auxiliary electrode is spaced at 10 μm to 40 μm from the second electrode. The first auxiliary electrode is preferably spaced at 40 μm from the first electrode, and the second auxiliary electrode is preferably spaced at 40 μm from the second electrode. 
     The first auxiliary electrode is electrically connected to the first electrode, and the second auxiliary electrode is electrically connected to the second electrode. 
     A plasma display panel according to another aspect of the present invention includes a plurality of the first and second electrodes provided at the rear side of an upper substrate; and auxiliary electrodes provided between the first and second electrodes. 
     In the plasma display panel, the width of the auxiliary electrode is set to 60 μm to 140 μm. The width of the auxiliary electrode is preferably set to 100 μm. 
     The auxiliary electrode is spaced at 60 μm to 100 μm from the first and second electrodes. 
     A method of driving a plasma display panel according to still another aspect of the present invention includes the steps of alternately applying the first and second sustain pulses to first and second electrodes in a sustain period; and applying a first auxiliary pulse synchronized with the first and second sustain pulses to an auxiliary electrode. 
     The method further includes the steps of applying a second auxiliary pulse between the first sustain pulses; and applying a third auxiliary pulse between the second sustain pulses in such a manner to be alternated with the second auxiliary pulse. 
     In the method, the second auxiliary pulse is applied simultaneously with the first auxiliary pulse supplied between the first sustain pulses, and the third auxiliary pulse is applied simultaneously with the first auxiliary pulse supplied between the second sustain pulses. 
     The first to third auxiliary pulses have the same pulse width. 
     The first to third auxiliary pulses have narrower pulse widths than the first and second sustain pulses. 
     Said pulse widths of the first to third auxiliary pulses are set to 0.5 μm to 1.5 μm. Preferably, said pulse widths of the first to third auxiliary pulses are set to 0.6 μm to 1.0 μm. 
     The first auxiliary pulse has a voltage value of −150V to −170V. Preferably, Each of the second and third auxiliary pulses has a voltage value of 50V to 60V. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects of the invention will be apparent from the following detailed description of the embodiments of the present invention with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view showing a discharge cell structure of a conventional AC surface-discharge plasma display panel; 
         FIG. 2  depicts gray levels of one frame of the plasma display panel shown in  FIG. 1 ; 
         FIG. 3  is a waveform diagram of a driving signal applied to each electrode of the plasma display panel for each sub-field; 
         FIG. 4  is a detailed view showing a structure of the electrodes provided on the upper substrate; 
         FIG. 5  illustrates electrodes provided on an upper substrate of a plasma display panel according to the first embodiment of the present invention; 
         FIG. 6  is a graph representing an efficiency of the plasma display panel; 
         FIG. 7  is a graph representing a brightness value of the plasma display panel; 
         FIG. 8  is a graph representing an efficiency of the plasma display panel according to positions of the auxiliary electrodes shown in  FIG. 5 ; 
         FIG. 9  is a graph representing an efficiency of the plasma display panel according to a space between the auxiliary electrodes and the first and second electrodes shown in  FIG. 5 ; 
         FIG. 10  is a graph representing an efficiency of the plasma display panel according to widths of the auxiliary electrodes shown in  FIG. 5 ; 
         FIG. 11  illustrates a discharge cell structure of a plasma display panel according to a second embodiment of the present invention; 
         FIG. 12  is a waveform diagram of a driving signal applied to each electrode shown in  FIG. 11  in the sustain period; 
         FIG. 13A  to  FIG. 13C  represents wall charges formed at the discharge cell when the driving waveform shown in  FIG. 12  is applied; 
         FIG. 14  is a graph representing an efficiency of the plasma display panel according to width of the auxiliary electrode shown in  FIG. 11 ; 
         FIG. 15  is a graph representing an efficiency value of the plasma display panel according to a space between the auxiliary electrode and the first and second electrodes shown in  FIG. 11 ; 
         FIG. 16  is a graph representing an efficiency value of the plasma display panel according to widths of the first and second electrodes shown in  FIG. 11 ; 
         FIG. 17  is a graph for comparing a brightness value of the conventional plasma display panel with that of the plasma display panel according to the second embodiment of the present invention; 
         FIG. 18  is a graph for comparing power consumption of the conventional plasma display panel with that of the plasma display panel according to the second embodiment of the present invention; and 
         FIG. 19  is a graph for comparing an efficiency of the conventional plasma display panel with that of the second embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 5  shows an upper substrate of a plasma display panel (PDP) according to the first embodiment of the present invention. 
     Referring to  FIG. 5 , the upper substrate of the PDP is provided with the first and second electrodes  32 Y and  32 Z. Each of the first and second electrodes  32 Y and  32 Z is a transparent electrode made from ITO. Since the ITO has a high resistance value, the rear sides of the first and second electrodes  32 Y and  32 Z are provided with bus electrodes  33 Y and  33 Z made from a metal, respectively. The bus electrodes  33 Y and  33 Z supply a driving signal from the exterior to the first and second electrodes  32 Y and  32 Z to thereby apply a uniform voltage to each discharge cell. 
     On the upper substrate provided with the first electrode  32 Y and the second electrode  32 Z in parallel, an upper dielectric layer  36  are disposed. Wall charges generated upon plasma discharge are accumulated into the upper dielectric layer  36 . A protective layer (not shown) is provided on the upper dielectric layer  36 . 
     First and second auxiliary electrodes  34 Y and  34 Z are provided within the upper dielectric layer  36 . The first auxiliary electrode  34 Y is formed at the edge of the discharge cell in such a manner to overlap with the first electrode  32 Y. The second auxiliary electrode  34 Z is formed at the edge of the discharge cell in such a manner to overlap with the second electrode  32 Z. 
     The first and second auxiliary electrodes  32 Y and  32 Z allow a sustain discharge to be generated at the entire discharge cell. To this end, the first auxiliary electrode  34 Y is electrically connected to the first electrode  32 Y while the second auxiliary electrode  34 Z is electrically connected to the second electrode  32 Z. 
     In other words, the same voltage as the first electrode  32 Y is applied to the first auxiliary electrode  34 Y, whereas the same voltage as the second electrode  32 Z is applied to the second auxiliary electrode  34 Z. Accordingly, a voltage at the edge of the discharge cell becomes higher than a voltage at the center of the discharge cell in the sustain period. If so, a sustain discharge is generated entirely without concentrating on the center of the discharge cell to thereby improve discharge efficiency. 
     For instance, the PDP according to the first embodiment has a higher efficiency than the conventional PDP as shown in FIG.  6 . In  FIG. 6 , the X axis represents a sustain voltage value applied to the first and second electrodes  32 Y and  32 Z while the Y axis does an efficiency value obtained by dividing brightness by power consumption. As can be seen from  FIG. 6 , the PDP according to the first embodiment has a higher efficiency (i.e., improvement of about 90%) than the conventional PDP. 
       FIG. 7  is a graph representing a brightness value of the PDP according to the first embodiment of the present invention. 
     Referring to  FIG. 7 , the PDP according to the first embodiment has a higher brightness value than the conventional PDP. Herein, the X axis represents a sustain voltage value applied to the first and second electrodes  32 Y and  32 Z while the Y axis does a brightness value of the PDP. In the PDP according to the first embodiment, a brightness rises in accordance with a rise in a sustain voltage value as shown in FIG.  7 . Further, the PDP according to the first embodiment when a voltage of 170V is applied to the first and second electrodes  32 Y and  32 Z has about 400 cd/m 2  higher brightness value than the conventional PDP when a voltage of 200V is applied. Accordingly, the PDP according to the first embodiment can be driven with a low voltage. 
       FIG. 8  is a graph representing an efficiency value depending upon positions of the auxiliary electrodes of the PDP according to the first embodiment of the present invention. 
     Referring to  FIG. 8 , as the first and second auxiliary electrodes  34 Y and  34 Z go into the center of the discharge cell, an efficiency of the PDP is lowered. Otherwise, as the first and second auxiliary electrodes  34 Y and  34 Z go into the edge of the discharge cell, an efficiency of the PDP is increased. Meanwhile, if the first and second auxiliary electrodes  34 Y and  34 Z do not overlap with the first and second electrodes  32 Y and  32 Z, then an efficiency of the PDP is lowered. Therefore, the first and second auxiliary electrodes  34 Y and  34 Z are provided to overlap with the first and second electrodes  32 Y and  32 Z. 
       FIG. 9  is a graph representing an efficiency value depending upon a space between the auxiliary electrodes and the first and second electrodes of the PDP according to the first embodiment of the present invention. 
     Referring to  FIG. 9 , as a distance between the first and second auxiliary electrodes  34 Y and  34 Z and the first and second electrodes  32 Y and  32 Z go wider, an efficiency of the PDP is increased. Thus, when the upper dielectric layer  36  is formed at a thickness of 45 μm, the first and second auxiliary electrodes  34 Y and  34 Z is spaced at a distance of above 40 μm from the first and second electrodes  32 Y and  32 Z. 
       FIG. 10  is a graph representing an efficiency value depending upon widths of the auxiliary electrodes of the PDP according to the first embodiment of the present invention. 
     Referring to  FIG. 10 , it can be seen that, as the first and second auxiliary electrodes  34 Y and  34 Z go wider, an efficiency of the PDP is increased. In other words, the efficiency of the present PDP suddenly rises until the widths of the first and second auxiliary electrodes  34 Y and  34 Z are 40 μm, and slowly rises after they are 40 μm. Meanwhile, as the widths of the first and second auxiliary electrodes  34 Y and  34 Z go wider, the greater power is wasted. Thus, the first and second auxiliary electrodes  34 Y and  34 Z are set to be about 40 μm. 
       FIG. 11  shows a discharge cell structure of a plasma display panel according to a second embodiment of the present invention. 
     Referring to  FIG. 11 , the PDP according to the second embodiment includes the first electrode  42 Y and a second electrode  42 Z provided on an upper substrate  40 , and an address electrode  54 X provided on a lower substrate  56 . 
     Each of the first and second electrodes  42 Y and  42 Z is a transparent electrode made from ITO. Since the ITO has a high resistance value, the rear sides of the first and second electrodes  42 Y and  42 Z are provided with bus electrodes  43 Y and  43 Z made from a metal, respectively. The bus electrodes  43 Y and  43 Z supply a driving signal from the exterior to the first and second electrodes  42 Y and  42 Z to thereby apply a uniform voltage to each discharge cell. Between the first electrode  42 Y and the second electrode  42 Z, an auxiliary electrode  44  is provided in parallel to the first and second electrodes  42 Y and  42 Z. 
     On the upper substrate  40  provided with the first electrode  42 Y and the second electrode  42 Z in parallel, an upper dielectric layer  46  and a protective film  48  are disposed. Wall charges generated upon plasma discharge are accumulated into the upper dielectric layer  46 . The protective layer  48  prevents a damage of the upper dielectric layer  46  caused by a sputtering during the plasma discharge and improves the emission efficiency of secondary electrons. This protective layer  48  is usually made from magnesium oxide (MgO). 
     A lower dielectric layer  52  and barrier ribs (not shown) are formed on the lower substrate  56  provided with the address electrode  54 X. The surfaces of the lower dielectric layer  52  and the barrier ribs are coated with a Phosphor layer  50 . The address electrode  54 X is formed in a direction crossing the first electrode  42 Y and the second electrode  42 Z. 
       FIG. 12  is a waveform diagram of driving signals applied to the auxiliary electrode, the first electrode and the second electrode in the sustain period in the PDP according to the second embodiment of the present invention. 
     Referring to  FIG. 12 , the first and second sustain pulses SUSPy and SUSPZ are alternately applied to the first and second electrodes  42 Y and  42 Z. Whenever the first and second sustain pulses SUSPy and SUSPz are applied to the first and second electrodes  42 Y and  42 Z, the first auxiliary pulse A 1  is applied to the auxiliary electrode  44 . 
     Further, a second auxiliary pulse A 2  is applied to the first electrode  42 Y between the first sustain pulses SUSPy. A third auxiliary pulse A 3  is applied to the second electrode  42 Z between the second sustain pulses SUSPz. 
     These second and third auxiliary pulses A 2  and A 3  are alternately supplied with being synchronized with the first auxiliary pulse A 1 . 
     The first auxiliary pulse A 1 , the second auxiliary pulse A 2  and the third auxiliary pulse A 3  have the same pulse width T 2 . Each of the first, second and third auxiliary pulses A 1 , A 2  and A 3  has a pulse width of about 0.5 to 1.5 μs, and has preferably a pulse width of about 0.6 to 1.0 μs. The first and second sustain pulses SUSPy and SUSPz have a wider pulse width T 1  than the first to third auxiliary pulses A 1  to A 3 . The pulse width T 1  of the sustain pulses SUSPy and SUSPz is set to be about 3 μs. Meanwhile, a voltage of the first auxiliary pulse A 1  is set to a range of −150V to −170V, and voltages of the second and third auxiliary pulses A 2  and A 3  are set to a range of 50V to 60V. 
     Hereinafter, a sustain operation of the PDP according to the second embodiment of the present invention with reference to  FIG. 13A  to FIG.  13 C. 
     The first, it is assumed that, as shown in  FIG. 13A , positive wall charges are formed at the first electrode  42 Y while negative wall charges are formed at the second electrode  42 Z and the auxiliary electrode  44 . Then, a negative the first auxiliary pulse A 1  is applied to the auxiliary electrode  44 . 
     If a negative first auxiliary pulse A 1  is applied to the auxiliary electrode  44 , then positive wall charges are formed at the auxiliary electrode  44  as shown in FIG.  13 B. At this time, a positive third auxiliary pulse A 3  is applied to the second electrode  42 Z. Thus, negative wall charges formed at the second electrode  42 Z are kept or enhanced. 
     Subsequently, a negative second sustain pulse SUSPz is applied to the second electrode  42 Z. If a negative second sustain pulse SUSPz is applied to the second electrode  42 Z, then a discharge is generated between the second electrode  42 Z and the auxiliary electrode  44 . In other word, since positive wall charges are formed at the auxiliary electrode  44 , a discharge is initiated between the auxiliary electrode  44  and the second electrode  42 Z. Then, a sustain discharge is generated between the first electrode  42 Y and the second electrode  42 Z. 
     The PDP according to the second embodiment forms positive wall charges at the auxiliary electrode  44 , so that it can cause a sustain discharge between the first electrode  42 Y and the second electrode  42 Z. In other words, the present PDP forms positive wall charges at the auxiliary electrode  44 , so that it may cause a sustain discharge between the first electrode  42 Y and the second electrode  42 Z by a low voltage. 
     If a sustain discharge occurs between the first electrode  42 Y and the second electrode  42 Z, then negative wall charges are formed at the first electrode  42 Y, positive wall charges are formed at the second electrode  42 Z, and negative wall charges are formed at the auxiliary electrode  44 , as shown in FIG.  13 C. Then, a negative first auxiliary pulse A 1  is applied to the auxiliary electrode  44  to form positive wall charges. The present PDP repeats a process as mentioned above to generate a sustain discharge. 
       FIG. 14  is a graph representing an efficiency value according to a width of the auxiliary electrode. 
     It can be seen from  FIG. 14  that, as a width of the auxiliary electrode  44  goes wider, an efficiency of the PDP is increased. Herein, the X axis represents a width of the auxiliary electrode  44  while the Y axis does an efficiency value obtained by dividing brightness by power consumption. At this time, a space between the auxiliary electrode  44  and the first and second electrodes  42 Y and  42 Z is fixed to 60 μm, and a distance extending from the first and second electrodes  42 Y and  42 Z until the boundary portion of the discharge cell is fixed to 220 μm. Accordingly, as a width of the auxiliary electrode  44  goes wider, widths of the first and second electrodes  42 Y and  42 Z are reduced. 
     In the mean time, as shown in  FIG. 14 , an efficiency of the PDP is suddenly increased when a width of the auxiliary electrode  44  is increased from 60 μm into 100 μm; whereas it is slowly increased when a width of the auxiliary electrode  44  is increased from 100 μm into 140 μm. Thus, in the present embodiment, a width of the auxiliary electrode  44  is set to 60 μm to 140 μm, and is preferably set to 100 μm. 
       FIG. 15  is a graph representing an efficiency value according a space between the auxiliary electrode and the first and second electrodes. 
     It can be seen from  FIG. 15  that, as a space between the auxiliary electrode  44  and the first and second electrodes  42 Y and  42 Z goes wider, an efficiency of the PDP is increased. Herein, the Y axis represents an efficiency of the PDP while the X axis does a space between the auxiliary electrode  44  and the first and second electrodes  42 Y and  42 Z. A width of the auxiliary electrode  44  is fixed to 100 μm, and a distance extending from the first and second electrodes  42 Y and  42 Z until the boundary portion of the discharge cell is fixed to 220 μm. Thus, as a space between the auxiliary electrode  44  and the first and second electrodes  42 Y and  42 Z goes wider, widths of the first and second electrodes  42 Y and  42 Z are reduced. 
     As can be seen from  FIG. 15 , an efficiency of the PDP is suddenly increased when a space between the auxiliary electrode  44  and the first and second electrodes  42 Y and  42 Z is increased from 40 μm into 60 μm; whereas it is slowly increased when a space between the auxiliary electrode  44  and the first and second electrodes  42 Y and  42 Z is increased from 60 μm into 100 μm. In the present embodiment, a space between the auxiliary electrode  44  and the first and second electrodes  42 Y and  42 Z is set to 60 μm to 100 μm. 
       FIG. 16  is a graph representing an efficiency value according to widths of the first and second electrodes. 
     It can be seen from  FIG. 16  that an efficiency of the PDP is almost constant independently of widths of the first and second electrodes  42 Y and  42 Z. Herein, the X axis represents widths of the first and second electrodes  42 Y and  42 Z while the Y axis does an efficiency of the PDP. At this time, a width of the auxiliary electrode  44  is fixed to 100 μm while a space between the auxiliary electrode  44  and the first and second electrodes  42 Y and  42 Z is fixed to 60 μm. 
       FIG. 17  to  FIG. 19  are graphs for comparing brightness, power consumption and efficiency of the PDP according to the second embodiment of the present invention with those of the conventional PDP. 
     Herein, the PDP according to the second embodiment is measured by fixing a width of the auxiliary electrode  44  to 100 μm and setting a space between the auxiliary electrode  44  and the first and second electrodes  42 Y and  42 Z to 60 μm (at the first PDP), 80 μm (at the second PDP) or 100 μm (at the third PDP). A distance extending from the first and second electrodes  42 Y and  42 Z until the boundary portion of the discharge cell is fixed to 220 μm. 
     In the first PDP, a voltage of the first auxiliary pulse A 1  is set to −150V while voltages of the second and third auxiliary pulses A 2  and A 3  are set to 50V. In the second PDP, a voltage of the first auxiliary pulse A 1  is set to 150V while voltages of the second and third auxiliary pulses A 2  and A 3  are set to 60V. In the third PDP, a voltage of the first auxiliary pulse A 1  is set to −160V while voltages of the second and third auxiliary pulses A 2  and A 3  are set to 60V. 
       FIG. 17  is a graph representing a brightness value according to a variation in a sustain voltage. 
     Referring to  FIG. 17 , the PDP&#39;s according to the embodiments of the present invention have a higher brightness value than the conventional PDP. For example, when a voltage of −200V is applied to the first and second electrodes  42 Y and  42 Z, the second PDP has the highest brightness value and the conventional PDP has the lowest brightness value. More specifically, when a voltage of −200V is applied to the first and second electrodes  42 Y and  42 Z, the second PDP has a brightness value of 767 cd/m 2 ; the third PDP has a brightness value of 765 cd/m 2 ; and the first PDP has a brightness value of 688 cd/m 2 . On the other hand, the conventional PDP have a brightness value of 348 cd/m 2 . In other words, the PDP&#39;s according to the second embodiment of the present invention have a brightness value improved at approximately 80 to 100% in comparison to the conventional PDP. 
       FIG. 18  is a graph representing a power consumption value according a variation in a sustain voltage. 
     It can be seen from  FIG. 18  that the PDP&#39;s according to the second embodiment waste greater power than the conventional PDP. For example, when a voltage of −200V is applied to the first and second electrodes  42 Y and  42 Z, the conventional PDP wastes about 0.000642W. On the other hand, the third PDP wastes about 0.000657W; the second PDP wastes about 0.000686W; and the first PDP wastes about 0.000693W. In other words, the PDP&#39;s according to the second embodiment have 10% higher power consumption than the conventional PDP. 
       FIG. 19  is a graph representing an efficiency of the PDP according to a variation in a sustain voltage. 
     It can be seen from  FIG. 19  that the PDP&#39;s according to the second embodiment have a higher efficiency than the conventional PDP. For example, when a voltage of −200V is applied to the first and second electrodes  42 Y and  42 Z, the third PDP has an efficiency of 1.821 m/W; the second PDP has an efficiency of 1.731 m/W; and the first PDP has an efficiency of 1.521 m/W. On the other hand, the conventional PDP has an efficiency of 0.881 m/W. In other words, the PDP&#39;s according to the second embodiment have an efficiency improved at about 80 to 100% in comparison to the conventional PDP. 
     Although the present invention has been explained by the embodiments shown in the drawings described above, it should be understood to the ordinary skilled person in the art that the invention is not limited to the embodiments, but rather that various changes or modifications thereof are possible without departing from the spirit of the invention. Accordingly, the scope of the invention shall be determined only by the appended claims and their equivalents.