Abstract:
A plasma display panel driving system and method for a display panel having a first common electrode and first independent electrodes arranged at a back plate side, a second common electrode and second independent electrodes arranged at a face plate side, an inner partition positioned between the first common and independent electrodes at the back plate side and the second common and independent electrodes at the face plate side and having an aperture therein connecting a space at the back plate side and a space at the face plate side, and a fluorescent layer arranged in the space at the face plate side. The driving system and method includes a driver for driving the first and second independent and common electrodes through a full writing period, a front surface erasing period, a writing period, and a discharge sustaining period, including supplying a first full writing pulse to the first common electrode at the back plate side and a second full writing pulse having a polarity which is opposite to the polarity of the first full writing pulse to the first independent electrodes at the back plate side for causing discharge between the first common and independent electrodes in the full writing period.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is related to copending U.S. application Ser. No. 08/525,975, entitled Gas Discharge Display Panel and Method Thereof, filed by all of the inventors herein and others, on Sep. 7, 1995. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to a memory type AC plasma display panel driving system and method used in a display device such as a personal computer or a work-station and a display device such as a flat wall-hanging type television or an advertisement or the like. 
     The prior art AC plasma display device is operated such that one light emitting display period is comprised of a full writing period, erasing period, a writing (address) period and a discharge sustaining period as disclosed Japanese Patent Application Laid-Open No. Hei 5-188877, for example, and pulses are applied to the X electrodes at the front surface side for the full writing operation and erasing operation. 
     However, in the prior art system described above, since the full writing is carried out by the electrodes at the front surface side of the display device, a phenomenon occurs that light emission occurs with the full writing even in the case that a black color displaying, i.e. a light emitting display is not performed, and further the black color is not displayed as a black color, but rather is displayed as a gray color and shows a problem that a contrast is decreased. 
     The present inventors and others, to solve such problems, invented a new plasma display panel as described in the copending application. The panel has a face plate, a back plate and a partition disposed therebetween. The face plate has a common electrode and a plurality of independent electrodes, and the back plate has a common electrode and a plurality of independent electrodes disposed perpendicular to those electrodes in the front panel so as to be able to do full writing in the back plate side. Further, the present inventors have developed a driving system and method for such plasma display panel. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a plasma display panel driving system and method in which contrast is improved. 
     It is another object of the present invention to provide a plasma display panel driving system and method in which discharging between electrodes at a back plate side is performed during the full writing period. 
     It is still another object of the present invention to provide a plasma display panel driving system and method in which any discharging during the full writing period is not carried out at the front plate side. 
     According to the present invention, the plasma display panel driving system includes a common electrode arranged at a back plate side, an independent electrode arranged parallel to and alternatively with the common electrode at the back plate side, a common electrode is arranged at a front or face plate side and extends transversely with respect to the electrodes arranged at the back plate side, an independent electrode is arranged parallel to and alternatively with the common electrode at the face plate side, an inner partition positioned between the electrodes at the back plate side and the electrodes at the face plate side and has an aperture connected between the space at the back plate side and the space at the face plate side, a fluorescent member or layer is arranged in the space at the face plate side, and a driver generator is provided for driving the electrodes through a full writing period, a front surface erasing period, a writing period, and a discharge sustaining period in each sub-field period and for supplying a first full writing pulse to the common electrode at the back plate side and for supplying a second full writing pulse whose polarity is opposite to the first full writing pulse to the independent electrode at the back plate side for enabling a discharge between the electrodes in the full writing period. 
     In accordance with the present invention, each of the light emitting display periods is divided into a full writing period, a front surface erasing period, a writing period and a discharge sustaining period, wherein full writing electrical discharging in the full writing period is carried out by the independent electrode and the common electrode arranged at the back plate side in the rear surface space having no fluorescent members, so that the light reaching the front surface side is merely a part of the electrical discharged light. Due to this fact, a volume of light reaching the front surface side is reduced and non-required light is reduced, so that contrast is improved. 
     The plasma display panel driving system further comprises a protecting pulse generator for supplying a protecting pulse to the independent electrode at the front or face plate side during the full writing period. The protecting pulse protects a discharging carried out between the electrode and the electrode at the back side plate. 
     According to a feature of the invention, a full writing pulse generator and a protecting pulse generator, etc. are used for driving the driving system. 
     These and other objects, features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view illustrating a part of a structure of the plasma display panel. 
     FIG. 2 is a sectional view in the direction of arrow A in the plasma display panel of FIG.  1 . 
     FIG. 3 is a sectional view in the direction of arrow B of the plasma display panel of FIG.  1 . 
     FIG. 4 is a top plan view illustrating a part of the electrode at the face plate in FIG.  1 . 
     FIG. 5 is a top plan view illustrating a combination of electrodes for performing a main electrical discharging of cells at the face plate in FIG.  1 . 
     FIG. 6 is a top plan view illustrating an enlarged one pixel in the inner partition in FIG.  1 . 
     FIG. 7 is a top plan view illustrating a part of the electrode at the back plate of FIG.  1 . 
     FIGS.  8 ( a )-( c ) are time-charts for one field period in a preferred embodiment of the driving system of the plasma display panel of the present invention. 
     FIGS.  9 ( a )-( d ) are diagrams illustrating waveforms representing the driving waveforms of the sub-field period in the preferred embodiment of the driving system of the plasma display panel of the present invention. 
     FIGS.  10 ( a )-( d ) illustrate an applied driving waveform of a sub-field period of a cell from which no light is emitted in one preferred embodiment of the driving system of the plasma display panel of the present invention. 
     FIG. 11 illustrates a driving system in accordance with an embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, wherein like reference numerals are utilized to designate like parts throughout the several views, FIG. 1 is an exploded perspective view illustrating a part of the structure of the plasma display panel of the copending application utilized by the driving system of the present invention. Reference numeral  15  denotes a front or face glass plate having a common X electrode, an independent Y electrode  17 , an X bus electrode  18 , a Y bus electrode  19 , a dielectric layer  20 , and a protective layer  21  provided thereon. The panel also includes a back plate  22  having a common a electrode  23 , an independent A electrode  25 , a dielectric layer  26 , and a protective layer  27  provided thereon. The panel also includes front and back partitions  28 , a side partition  29 , an inner partition  30 , and an aperture  31 , respectively. The electrode  16  is a transparent common X electrode  16  and the electrode  17  is a transparent independent Y electrode  17  which are arranged in parallel to one another at the lower surface of the face plate  15 . In addition, the X bus electrode  18  is stacked on the common X electrode  16  and the Y bus electrode  19  is stacked on the independent Y electrode  17 , respectively. Then, these electrodes are covered by the dielectric layer  20  and the protective layer  21  of MgO or the like. 
     In turn, the common a electrode  23  is arranged at the surface of the back plate  22  in a direction extending transversely or perpendicular to the electrodes on the front or face plate  15  and further there is provided the independent A electrodes  25  in parallel with the common a electrode  23 , and these electrodes are covered by the dielectric layer  26  and the protective layer  27  of MgO or the like. 
     Between the face base plate  15  and the back base plate  22  is arranged the inner partition  30  having front and back partitions  28  for dividing a space between the base plates into an electrical discharging space (a main electrical discharging space) at the front surface (i.e. the face plate  15 ) and an electrical discharging space (a preliminary electrical discharging space) at the rear surface (i.e. the back plate  22 ) and having a side partition  29  for dividing each of the display cells. The inner partition  30  at the face plate  15  side is coated with a fluorescent member emitting light by a vacuum ultraviolet ray generated during electrical discharging. 
     In addition, the front and back partitions  28  are provided with apertures  31  for use in electrical discharging between the electrodes arranged at the face plate  15  and the electrodes arranged at the back plate  22 . Further, an electrical discharging gas such as a rare gas as, for example, a neon gas with several percent of xenon gas is charged in these electrical discharging spaces. 
     FIG. 2 is a sectional view of the plasma display panel as seen from an arrow A in FIG. 1, wherein  32  denotes the main electrical discharging space,  33  denotes the preliminary electrical discharging space, and  34  denotes a fluorescent material layer. In this figure, the common a electrode  23  and the independent A electrode  25  are arranged in parallel to each other between the side partitions  29  on the back plate  22 . Then, at the main electrical discharging space  32 , the surface of the front and back partition  28  and the surface of the side partition  29  are coated with the fluorescent material layer  34 , other than the preliminary electrical discharging space  33 . In addition, the apertures  31  arranged at the front and back partition  28  for dividing the main electrical discharging space  32  and the preliminary electrical discharging space  33  are positioned above the independent A electrode  25 . 
     FIG. 3 is a sectional view of the a plasma display panel as seen from an arrow B in FIG.  1 . In this figure, the apertures  31  arranged at the front and back partitions  28  are positioned below the independent Y electrode  17 . Accordingly, as viewed from FIG. 2, the apertures  31  are located at the crossing positions between the independent Y electrode  17  and the independent A electrode  25 . 
     FIG. 4 is a top plan view illustrating a part of each of the common X electrode  16  and the independent Y electrodes  17  at the face plate  15  in FIG.  1 . In this figure, although each of the independent Y electrodes  17  is made independent respectively, all of one ends of portions of the common X electrode  16  which extend in parallel with the independent Y electrode  17  are connected to each other. 
     FIG. 5 is a top plan view illustrating, in an enlarged scale, a part of the electrode structure for performing a main electrical discharging at the face plate  15 . In this figure, one common X electrode  16  and the independent Yi electrode  17  form a set so as to perform a main electrical discharging of one cell. In addition, another common X electrode  16  and the independent Yi+2 electrode  17  form another set so as to perform a main electrical discharging of the adjoining cell. 
     FIG. 6 is a top plan view illustrating, in an enlarged scale, one pixel of the inner partition  30  in FIG. 1, wherein  34 R,  34 G and  34 B denote fluorescent members and  35  to  37  denote cells. In this figure, the adjoining three cells  35 ,  36  and  37  are coated with fluorescent members  34 R,  34 B and  34 G generating red light, blue light and green light, respectively, wherein one pixel is formed by these three cells  35 ,  36  and  37 . 
     FIG. 7 is a top plan view illustrating, in an enlarged scale, a part of the electrode at the back plate  22  in FIG.  1 . In this figure, although each of the independent A electrodes  25  is independent from one another, one end of portions of the common a electrode  23  extending in parallel with the independent A electrodes  25  are connected to each other. 
     The inner partition  30  of the panel is held and sealed by the front surface glass base plate  15  and the back plate  22  having the aforedescribed structure, and the electrical discharge gas is provided in the areas delimited by the partition to construct the plasma display panel. 
     FIGS.  8 ( a )-( c ) illustrate a driving timing of one field corresponding to the displaying period of one image. As shown in FIG.  8 ( a ), one field period corresponding to a displaying period of one image is divided into eight sub-fields  41  to  48 , wherein each of the sub-fields  41  to  48  is, as shown in FIGS.  8 ( b ) and ( c ),divided into a full writing period  49 , a front surface erasing period  50 , a writing period  51 , an electrical discharge sustaining period  52  and a blank period  53 . The number of the discharge sustaining pulses are, for example,  1 ,  2 ,  4 ,  8 ,  16 ,  32 ,  64 ,  128 , but the numbers of pulses may take same number in different sub-fields. 
     FIGS.  9 ( a )-( d ) illustrate driving waveforms of the plasma display panel in each of the sub-fields, wherein FIG.  9 ( a ) indicates a driving waveform applied to the common electrode a electrode  23  arranged at the back plate  22  and this is comprised of the full writing pulses  1 , and FIG.  9 ( b ) indicates a driving waveform applied to the independent A electrodes  25  arranged at the back plate  22 , and this is comprised of the full writing pulse  2  and the writing pulse  3 . The full writing pulses  1  and  2  are applied at substantially the same time, i.e. concurrently. 
     FIG.  9 ( c ) indicates a driving waveform applied to the independent Y electrodes  17  arranged at the face plate  15  and this is comprised of a protecting pulse  4 , a short erasing pulse  5 , a writing pulse  6  and electrical discharge sustaining pulses  7 . The writing pulses  3 ,  6  which have opposite polarities are applied at approximately the same time, and pulse widths are approximately 1 to 4 μsec. FIG.  9 ( d ) indicates a driving waveform applied to the common X electrode  16  arranged at the face plate  15 , wherein this waveform is comprised of a protecting pulse  8 , a short erasing pulse  9 , a pulling-up pulse  10  and electrical discharge sustaining pulses  11 . The protecting pulses  4 ,  8  are applied at approximately the same time beginning at a time about 10 μsec before the application of the full writing pulses  1 ,  2  and being continuously applied up to a time of at least about 10 μsec after the application of the full writing pulses  1  and  2 . The full writing pulses are applied to all the independent A electrodes  25 , and thee protecting pulses  4  are applied to all the independent Y electrodes  17 . 
     At the full writing period  49  at each of the sub-fields  41  to  48  shown in FIGS.  8 ( a )-( c ), the full writing electrical discharge is carried out at the preliminary electrical discharging space  33  (FIGS. 2 and 3) with the full writing pulse  2  applied to the independent A electrodes  25  arranged at the back plate  22  and the full writing pulse  1  applied to the common a electrode  23 . With such an arrangement as described above, states of electrical loads of all cells at the back plate  22  are made uniform. Since the full writing electrical discharging is carried out in the preliminary electrical discharging space  33  having no fluorescent material layer, the light emission is carried out only with the electrical discharged light of the gas electrically discharging in the discharging space  33 . In addition, at a part other than the apertures  31 , since the preliminary electrical discharging space  33  is shielded by the front and back partition  28 , light only reaches the face plate  15  through the apertures  31  and a reduced light reaches the face plate  15 . 
     In case of supplying the full writing pulses  1  and  2  to the common a electrode  23  and to the independent A electrodes  25  respectively, the following defects arises. To supply the full writing pulse  2  to the independent A electrode, a voltage which rises at  60   a  is supplied before the full writing pulse  2  to the independent A electrodes  25 . At such time, there arises the possibility of an occurrence of a discharge between the independent A electrodes  25  and the independent Y electrodes  17 . The occurrence of the discharging depends upon the condition of the air around the electrodes  17  and  25 . If the air in the vicinity of the electrodes  17  and  25  is ionized, the discharging easily occurs at the rising edge  60   a  of the voltage. 
     To prevent the discharging between the independent A electrodes  25  and the independent Y electrodes  17  at the rising edge  60   a , the protecting pulse  4  which rises at the same time with the rising edge  60   a  is supplied to the independent Y electrodes  17 . The voltage of both independent A electrodes  25  and the common a electrode  23  are maintained at zero through the discharge sustaining period, so that plus or minus electric charges which are produced during the discharge sustaining period do not exist around the electrodes  23  and  25 , and a voltage difference caused by the electric charge does not occur. Therefore, the voltage actually supplied to the independent A electrodes  25  is the voltage difference between the independent A electrodes  25  and the common a electrode  23 . The level of the voltage supplied to the independent A electrodes  25  is determined such that the discharging does not occur between the independent A electrodes  25  and the common a electrode  23 . 
     According to an experiment by the inventors, it is suitable for the plasma display panel illustrated in FIG. 1 that the voltage supplied to the independent A electrodes  25  is 150 volts or less, the full writing pulse  1  is 200-300 volts, and the protecting pulse  4  and  8  are 150-200 volt. 
     In case the interval of the rising edge  4   a  of the protecting pulse  4  and falling edge  2   a  of full writing pulse  2  is short, there is a possibility of an occurrence of discharge between the rising edge  4   a  of the protecting pulse  4  and the falling edge  2   a  of the writing pulse  2 . To prevent the discharging, the interval between edge  4   a  of the protecting pulse and the falling edge  2   a  of the writing pulse  2  is made 10 μsec or more. 
     The phenomena of the occurrence of the discharging is not fully resolved. In case the interval between the rising edge  4   a  of the protecting pulse  4  and the falling edge  2   a  of full writing pulse  2  is shorter than a predetermined period, a discharging is generated by the voltage difference between the voltage at the edge  4   a  of the protecting pulse  4  and the voltage at the edge  2   a  of the full writing pulse  2 . When the interval between the rising edge  4   a  and the falling edge  2   a  are longer than a predetermined period, minus electric charges gather in the vicinity of the independent A electrodes  25  and in the vicinity of the independent Y electrodes  17  because of the high voltage thereof, and the minus electric charge lowers the actual voltage difference. As a result, the discharge between the independent A electrodes  25  and the independent Y electrodes  17  does not occur. 
     In case the interval between the rising edge  2   b  of the full writing pulse  2  and the falling edge  4   b  of the protecting pulse  4  is shorter than a predetermined period, discharge between the independent A electrodes  25  and the independent Y electrodes  17  may occur for the following reasons. By supplying the full writing pulse  1  to the common a electrode  23  and supplying the full writing pulse  2  to the independent A electrodes  25 , a discharging between the common a electrode  23  and the independent A electrodes occurs. (Actually, the discharging occurs at the falling edge  2   a  of the writing pulse  2  and the rising edge  1   a  of the common a electrode  23 .) Plus electric charges gather in the vicinity of the independent A electrodes  25  during the period of supplying the full writing pulse  2 . The plus electric charges are added to the voltage at the edge  2   b  of the full writing pulse  2 . In case the interval of the edge  2   b  of the full writing pulse  2  and the edge  4   b  of the protecting pulse  4  is shorter than a predetermined period, discharging occurs between the independent A electrodes  25  and the independent Y electrodes  17 , because the plus electric charges are added to the voltage at the edge  2   b . In case the interval between the edges  2   b  and  4   b  is determined to be longer than a predetermined period, the voltage at the independent A electrodes  25  is maintained at a high voltage after the pulse  2 , and minus electric charges being to gather in the vicinity of the independent A electrodes  25 . As a result, the plus electric charges at the edge  2   b  are neutralized, or the voltage of the independent A electrodes  25  is actually reduced by the minus electric charges, and discharging between the independent A electrodes  25  and the independent Y electrodes  17  is prevented. 
     By the inventors&#39; experiment using the plasma panel disclosed in FIG. 1, it has that the discharging is prevented by making the interval between the edge  2   b  of the writing pulse  2  and the edge  4   b  of the protecting pulse  4  about 10 μsec or more. 
     As explained above, the discharging which may occur between the independent A electrodes  25  and the independent Y electrodes  17  during full the writing period is effectively prevented by supplying the protective pulse  4  to the independent Y electrodes  17 . 
     In case the protecting pulse  4  is supplied to the independent Y electrodes  17 , however, a discharging between the independent Y electrodes  17  and the common X electrode  16  has a possibility of occurrence because the voltage of the protecting pulse  4  is about 150-200 volts. To prevent this discharging, the protection pulse  8  which is substantially the same as the pulse  4  is supplied to the common X electrode  16 . By supplying the protection pulse  8  to the common X electrode  16 , the discharging between the independent Y electrodes  17  and the common X electrode  16  is prevented. Further, by supplying the protecting pulses  4  and  8  to the independent Y electrodes  17  and the common X electrode  16  respectively, the plus electric charge in the preliminary electrical discharging space  33  is restricted to move though the aperture  31  into the vicinity of the independent Y electrodes  17  and the common X electrode  16 . 
     As explained above, the discharging is formed in the preliminary electrical discharging space  33  by supplying the full writing pulse  1  to the common a electrode  23 , and by supplying the full writing pulse  2  to the independent A electrodes  25 . The discharging is formed in each sub-field period. Further, the protecting pulses  4  and  8  which are supplied to the independent Y electrodes  17  and the common X electrode  16 , respectively, protect the minus electric charges in the preliminary electrical discharging space  33  from moving into the main electrical discharging space  32  through the aperture  31 . 
     After this operation, at the front surface erasing period  50 , electrical loads of all cells at the front surface glass base plate  15  are eliminated by the short erasing pulse  9  applied to the common X electrode  16  arranged at the front surface glass base plate  15  and the short erasing pulse  5  applied to the independent Y electrodes  17 . The pulse width of the short erasing pulse  5  is narrower than the pulse width of the short erasing pulse  9 . 
     In case the main electrical discharging space  32  has plus electrical charges, a discharging occurs between the common X electrode  16  and the independent Y electrodes  17  by supplying the short erase pulse  9  to the common X electrode  16 . The discharging occurs mainly at the rising edge of the short erase pulse  9 . Minus electric charges which are generated by the discharging begin to gather in the vicinity of the common X electrode  16  at latter half of the short erase pulse  9 , and the plus electric charge in the main electrical discharging space  32  is neutralized by the minus electric charge. Then, the short erase pulse  5  which has a pulse width narrower than the short erase pulse  9  is supplied to the independent Y electrodes  17 . In case the main electrical discharging space  32  has electrical charges, a discharging is caused between the independent Y electrodes  17  and the common X electrode  16 . The pulse width of the short erase pulse  5  is so narrow that the short erase pulse  5  falls before the discharging is over and the electric charge generated by the discharging remains in the main electrical discharging space  32  for neutralization. 
     Subsequent to the front surface erasing period  50 , as shown in FIGS.  8 ( b ) and ( c ), there is provided a writing period  51  for restricting the cell for light emitting display. At the writing period  51 , the pulling-up pulse  10  is applied in such a manner that the common X electrode  16  shows a high potential level in advance in order to perform an effective utilization of the charged particles Generated by the writing electrical discharging. By supplying the pulling up pulse  10  to the common X electrode  16 , minus electric charges gather in the vicinity of the common X electrode  16  and plus electric charges gather in the vicinity of the independent Y electrodes  17 , and as a result, a discharging is certainly effected in the discharging sustaining period. That is, the voltage of the discharge sustaining pulses  7  and  11  are determined so as to effect discharging only in the presence of the electric charges and not to effect discharge without these electric charges. Before this operation, the writing electrical discharging is carried out with the writing pulse  3  of about 1 to 4 μsec applied to the independent A electrodes  25  arranged at the rear surface glass plate  22  and the writing pulse of about 1 to 4 μsec applied to the independent Y electrodes  17  arranged at the front surface glass base plate  15 . 
     In the writing period, writing pulses  6  whose pulses are deviated by a pulse width are supplied in sequence to the respective independent Y electrodes  17  (Y 1 , Y 2 , Y 3 , Ym) and the writing pulses  3  are supplied to the selected independent A electrodes. In case the writing pulse  6  is supplied to the Y 1  electrode, discharging occurs at the intersecting point of the Y 1  electrode  17  and the selected independent A electrodes  25 . Upon completion of the writing operation, the independent A electrodes  25  and the common X electrode  16  are returned to their lower potential in this order and the cell advances to the maintaining electrical discharging period  52 . 
     In addition, it is also possible that a potential between the writing pulse  3  applied to the independent A electrodes  25  and the writing pulse  6  applied to the independent Y electrodes  17  may be lower than a potential difference between the full writing pulses  1 ,  2  due to a surplus of the charged particles caused by the full writing electrical discharging. The discharge sustaining pulse  7  is supplied to the independent Y electrodes  17 , and the discharge sustaining pulse  11  is supplied to the common X electrode  16  during the discharge sustaining period. By the supplying of the discharge sustaining pulses  7  and  11 , discharge occurs only in the part where the electric discharge is generated during the writing period and the fluorescence is brightened by the discharging. The number of the discharge sustaining pulses  7  and  11  are determined in each sub-field. 
     FIGS.  10 ( a )-( d ) show a driving waveform of a cell in which light is not emitted. FIG.  10 ( a ) shows a driving waveform applied to the common a electrode  23 . FIG.  10 ( b ) shows a driving waveform applied to the independent A electrodes  25 , and as is apparent from comparison with FIG.  9 ( b ), only the full writing pulse  2  is applied and no writing pulse  3  is applied at the writing period  51 . Due to this fact, writing electrical discharge is not performed even through the writing pulse  6  is applied to the independent Y electrodes  17  as shown in FIG.  10 ( c ) and therefore no charged particles are generated. Accordingly, even if the maintaining pulses  7 ,  11  are applied and the driving waveforms applied to the common X electrode  16  as shown in FIG.  10 ( d ), electrical discharging is not produced. In this way, it is possible to drive the plasma display panel and further to prevent a reduction in contrast. 
     FIG. 11 shows a block diagram arrangement of a driving system wherein a pulse generator  71  supplies pulses in accordance with FIGS.  9 ( d ) and  10 ( d ) to the common X electrode  16 , a pulse generator  72  supplies pulses in accordance with FIGS.  9 ( c ) and  10 ( c ) to the independent Y electrodes  17 , a pulse generator  73  supplies pulses in accordance with FIGS.  9 ( b ) and  10 ( b ) to the independent A electrodes  25  and a pulse generator  74  supplies pulses in accordance with FIGS.  9 ( a ) and  10 ( a ) to the common a electrode  23 , with the pulse generators being controlled in timing by a timing generator  70 . 
     As described above, according to the present invention, it is possible to improve a contrast by driving the plasma display panel and reducing a light of full writing reaching to the front surface side. Further, according to the invention, unexpected discharge during full writing period is prevented and the operation is stabilized. 
     While we have shown and described embodiments in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to those skilled in the art, and we therefore do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.