Abstract:
A method and apparatus for driving a plasma display panel (PDP) with discharge cells arranged between a first substrate and second substrate, address electrodes arranged along a first direction, first electrodes and second electrodes arranged along a second direction crossing the first direction on opposite sides of each of a discharge cell, and scan electrodes arranged along the second direction that partition each discharge cell into two discharge spaces. The two discharge spaces of one discharge cell share a scan electrode. By selectively biasing the first electrodes and second electrodes during an address period, the two discharge spaces can be addressed during a first half and a second half of a single address period or during two distinct address periods. Sustain discharge for a single subfield can be generated in the two discharge spaces during a single sustain discharge period or during two distinct sustain discharge periods.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority to and the benefit of Korea Patent Application No. 10-2004-0102240, filed on Dec. 7, 2004, which is hereby incorporated by reference for all purposes as if fully set forth herein.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a plasma display panel (PDP), and, specifically, to a PDP having an improved structure and a method for driving thereof.  
         [0004]     2. Discussion of the Background  
         [0005]     Generally, a PDP is a display device which excites phosphors with vacuum ultraviolet (VUV) rays radiated from plasma obtained through gas discharge, and displays desired images by visible light generated by the excited phosphors.  
         [0006]     A PDP having a three-electrode surface-discharge scheme is an example of a general PDP. In a PDP with a three-electrode surface discharge scheme, display electrodes are arranged on a front substrate in pairs, and address electrodes are arranged on a rear substrate, which is separated from the front substrate by a predetermined gap. In addition, a space between the front and rear substrates is partitioned by barrier ribs to form a plurality of discharge cells. A phosphor layer is arranged in the discharge cells on a portion of the rear substrate and the discharge cells contain a discharge gas.  
         [0007]     Whether discharge is generated in a discharge cell depends upon an address discharge between one of the display electrodes and an address electrode arranged opposite to the display electrode. A sustain discharge displaying brightness is generated by the display electrodes located on the same surface. In a conventional PDP, the address discharge is generated as an opposed discharge and the sustain discharge is generated as a surface discharge.  
         [0008]     Although a distance between the display electrode and the address electrode is greater than the distance between the pair of display electrodes, the discharge firing voltage of the address discharge is a lower voltage than the discharge firing voltage of the sustain discharge. Since the address discharge is induced by an opposed discharge, it has a discharge firing voltage lower than the voltage of the sustain discharge induced by a surface discharge. Therefore, a PDP in which a sustain discharge can be induced by an opposed discharge can have higher efficiency than the conventional PDP.  
         [0009]     Discharge space in a PDP is divided into a sheath region and a positive column region. The sheath region refers to a non-light emitting region formed around where an electrode or dielectric layer is formed, in which most voltage is consumed. The positive column region refers to a region where a plasma discharge can be actively generated with a very low voltage. Therefore, to enhance efficiency of a PDP, the positive column region can be expanded. The length of the sheath region is not related to the discharge gap. Thus, expanding the positive column region can be achieved by increasing the discharge length. However, increasing the discharge gap to increase the discharge length may result in a high discharge firing voltage.  
         [0010]     Thus, in a conventional PDP, low discharge firing voltage and high efficiency could not be realized at the same time.  
         [0011]     Further, resolution is significantly related to display quality of a PDP. Therefore, there is an increasing need for a PDP in which resolution can be improved with the same area of discharge cells.  
         [0012]     The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.  
       SUMMARY OF THE INVENTION  
       [0013]     This invention provides a PDP with an improved structure.  
         [0014]     This invention also provides a method for driving a PDP with an improved structure.  
         [0015]     Additional features of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention.  
         [0016]     The present invention discloses a PDP including a first substrate, a second substrate disposed opposite to the first substrate and forming a space between the first substrate and second substrate, where the space is partitioned into a plurality of discharge cells, an address electrode arranged along a first direction, a first electrode electrically insulated from the address electrode and arranged at a first side of a discharge cell, along a second direction crossing the first direction, a second electrode electrically insulated from the address electrode and arranged at a second side of a discharge cell along a second direction crossing the first direction, where the second side is opposite to said first side, and a scan electrode arranged along the second direction between the first electrode and second electrode, and partitioning a discharge cell into a first discharge space and a second discharge space. Further, the first electrode is coupled with a first sustain line to form a first sustain electrode group, and the second electrode is coupled with a second sustain line to form a second sustain electrode group.  
         [0017]     The present invention also discloses a method of driving a PDP, including in a first address period, addressing a first discharge space in a discharge cell by biasing a first sustain electrode with a first voltage, biasing a second sustain electrode with a second voltage lower than the first voltage, and applying a third voltage, which is lower than the first voltage, to a scan electrode, and in a second address period, addressing a second discharge space in the discharge cell by biasing the first sustain electrode with the second voltage, biasing the second electrode with first voltage, and applying the third voltage to the scan electrode. The first discharge space is formed between the first sustain electrode and the scan electrode and the second discharge space is formed between the second sustain electrode and the scan electrode.  
         [0018]     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]     The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention.  
         [0020]      FIG. 1  shows an exploded perspective view of a PDP according to a first embodiment of the present invention.  
         [0021]      FIG. 2  shows a partial sectional view of the PDP according to the first embodiment, taken along line II-II in  FIG. 1 .  
         [0022]      FIG. 3  shows a partial perspective view showing electrodes of the PDP according to the first embodiment of the present invention.  
         [0023]      FIG. 4  shows a partial top plan view of the PDP according to the first embodiment of the present invention.  
         [0024]      FIG. 5  shows a driving waveform for illustrating a driving method of a PDP according to a second embodiment of the present invention.  
         [0025]      FIG. 6  shows a conceptual view of the driving method of the PDP according to the second embodiment of the present invention.  
         [0026]      FIG. 7  shows a driving waveform for illustrating a driving method of a PDP according to a third embodiment of the present invention.  
         [0027]      FIG. 8  shows a conceptual view of the driving method of the PDP according to a third embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0028]     The invention is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure is thorough, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. Like numerals throughout the accompanying drawings refer to like components.  
         [0029]      FIG. 1  shows an exploded perspective view of a PDP according to a first embodiment of the present invention, and  FIG. 2  shows a partial sectional view of the PDP according to the first embodiment, which is taken along line II-II in  FIG. 1 .  FIG. 3  shows a partial perspective view showing electrodes of the PDP according to the first embodiment of the present invention.  
         [0030]     Referring to  FIG. 1 , the PDP according to the present embodiment includes a first substrate  10  (hereinafter referred to as a “rear substrate”) and a second substrate  20  (hereinafter referred to as a “front substrate”), which are disposed opposite to each other and separated by a predetermined distance therebetween. A first barrier rib  16  (hereinafter referred to as a “rear-plate barrier rib”) and a second barrier rib  26  (hereinafter referred to as a “front-plate barrier rib”) are disposed between the rear substrate  10  and the front substrate  20 , and partition a plurality of discharge cells  38 . A first phosphor layer  19  is arranged on a portion of the rear substrate that corresponds to discharge cells  38 , and a second phosphor layer  29  is arranged on a portion of the front substrate that corresponds to discharge cells  38 . First phosphor layer  19  and second phosphor layer  29  can include red, green, and blue phosphors for absorbing VUV rays and emitting visible light. In addition, the discharge cells  38  are filled with a discharge gas, including for example a mixed gas such as xenon (Xe) or neon (Ne), so that VUV rays can be generated with plasma discharge.  
         [0031]     The rear-plate barrier rib  16  is formed adjacent to the rear substrate  10  and extends toward the front substrate  20 . The front-plate barrier rib  26  is formed adjacent to the front substrate  20 , extends toward the rear substrate  10 , and corresponds to the rear-plate barrier rib  16  to partition the plurality of discharge cells  38 . The rear-plate barrier rib  16  and the front-plate barrier rib  26  can partition the discharge cells  38  in a variety of shapes, such as rectangular, square, or hexagonal. The present embodiment illustrates the discharge cells  38  formed in a square shape.  
         [0032]     The rear-plate barrier rib  16  includes a first barrier rib member  16   a  arranged along a first direction (a y-axis direction in the drawings), a second barrier rib member  16   b  arranged along a second direction (a x-axis direction in the drawings), and a third barrier rib member  16   c  arranged in the second direction and positioned parallel to and between two second barrier rib members  16   b . The first barrier rib members  16   a  and the second barrier rib members  16   b  are arranged to cross each other to partition rear discharge cells  18  on a portion of the rear substrate  10 .  
         [0033]     In addition, the front-plate barrier rib  26  includes a fourth barrier rib member  26   a  arranged in a shape corresponding to the third barrier rib member  16   c , a fifth barrier rib member  26   b  arranged in a shape corresponding to the first barrier rib member  16   a , and a sixth barrier rib member  26   c  arranged in a shape corresponding to the second barrier rib member  16   b.    
         [0034]     Therefore, the fifth barrier rib members  26   b  and the sixth barrier rib members  26   c  are arranged to cross each other to partition front discharge cells  28  on a portion of the front substrate  20 . Further, each front discharge cell  28  may correspond to one rear discharge cell  18 .  
         [0035]     A rear discharge cell  18  and a front discharge cell  28  corresponding to the rear discharge cell  18  substantially form one discharge cell  38 .  
         [0036]     As shown in  FIG. 2 , a third barrier rib member  16   c  partitions a rear discharge cell  18  into two discharge spaces  18   a  and  18   b . A fourth barrier rib member  26   a  partitions a front discharge cell  28  into two discharge spaces  28   a  and  28   b . A discharge cell  38  is substantially partitioned into two discharge spaces  38   a  and  38   b , as shown in  FIG. 3 .  
         [0037]     Furthermore, a first phosphor layer  19  is arranged in the rear discharge cells  18 . The first phosphor layer  19  is formed on lateral sides of the barrier rib members  16   a ,  16   b , and  16   c  forming the rear-plate barrier rib  16 , and a bottom surface adjacent to the rear substrate  10  between the rear-plate barrier rib  16 . A second phosphor layer  29  is arranged in the front discharge cells  28 . The second phosphor layer  29  is formed on lateral sides of the barrier rib members  26   a ,  26   b , and  26   c  forming the front-plate barrier rib  26 , and a top surface adjacent to the front substrate  20  between the front-plate barrier rib  26 .  
         [0038]     Thus, the first phosphor layer  19  arranged within a rear discharge cell  18  and the second phosphor layer  29  arranged within a front discharge cell  28  that corresponds to the read discharge cell  18  can be formed using phosphors that emit visible light of the same color through collision of VUV rays generated by gas discharge.  
         [0039]     In the present embodiment, since the front phosphor layer  19  and second phosphor layer  29  capable of generating visible light are formed on both sides of a discharge cell  38 , brightness of the generated visible light may be improved.  
         [0040]     Meanwhile, the first phosphor layer  19  arranged in a rear discharge cell  18  can be formed by forming a dielectric layer (not shown) on the rear substrate  10 , forming the rear-plate barrier rib  16  thereon, and then coating phosphors on the dielectric layer (not shown). Alternately, the first phosphor layer  19  can be formed by forming the rear-plate barrier rib  16  on the rear substrate  10  and then coating phosphors thereon, without forming the dielectric layer on the rear substrate  10 .  
         [0041]     In the same manner, the second phosphor layer  29  arranged in a front discharge cell  28  can be formed by forming a dielectric layer (not shown) on the front substrate  20 , forming the front-plate barrier rib  26  thereon, and then coating phosphors on a dielectric layer (not shown). Alternately, the second phosphor layer  29  can be formed by forming the front-plate barrier rib  26  on the front substrate  20  and then coating phosphors thereon, without forming the dielectric layer on the front substrate  20 .  
         [0042]     Furthermore, the first phosphor layer  19  can be formed by etching a substrate made of glass, for example, corresponding to the shape of two discharge spaces  18   a  and  18   b  of a rear discharge cell  18 , and then coating phosphors thereon. In a similar manner, the second phosphor layer  29  can be formed by etching a substrate made of glass, for example, corresponding to the shape of two discharge spaces  28   a  and  28   b  of a front discharge cell  28  and then coating phosphors thereon. The rear-plate barrier rib  16  and the rear substrate  10  can be integrally formed of the same material. The front-plate barrier rib  26  and the front substrate  20  can be integrally formed of the same material.  
         [0043]     After sustain discharge, the first phosphor layer  19  and the second phosphor layer  29  absorb VUV rays from the inside of the rear discharge cells  18  and the front discharge cells  28  and then generate visible light toward the front substrate  20 . Visible light then passes through the second phosphor layer  29 . Thus, to minimize loss of visible light, the thickness of the second phosphor layer  29  can be lower than the thickness of the first phosphor layer  19 .  
         [0044]     In addition, an address electrode  12 , a first electrode  31 A, a second electrode  31 B, and a scan electrode  32  are provided corresponding to the discharge cells  38 , respectively, between the rear substrate  10  and the front substrate  20  (between the rear-plate barrier rib  16  and the front-plate barrier rib  26 , more exactly).  
         [0045]     The scan electrode  32  selects a discharge cell  38  to be turned on, and generates an address discharge during an address period together with the address electrode  12 . The first electrode  31 A and second electrode  31 B are sustain electrodes, and implement a predetermined brightness in a sustain discharge during a sustain period together with the scan electrode  32 . However, first electrode  31 A and second electrode  31 B may play a different role depending on an applied signal voltage. Thus, the present invention is not restricted thereto.  
         [0046]     In this embodiment, the same voltage is applied to the first electrodes  31 A in the PDP to form a first sustain electrode group, and the same voltage is applied to the second electrodes  31 B in the PDP to form a second sustain electrode group. The sustain electrode groups can be reduced by one electrode in a terminal region, so that the common same voltage is applied to the one electrode.  
         [0047]     In the present embodiment, the first electrode  31 A, the second electrode  31 B, the scan electrode  32 , and the address electrode  12  are arranged along the perimeter of a discharge cell  38 . They can be formed of metal electrodes with good electrical conductivity.  
         [0048]     The address electrode  12  is arranged in the first direction (the y-axis direction in the drawings), parallel to the first barrier rib member  16   a , and corresponds to the first barrier rib member  16   a  between the rear-plate barrier rib  16  and the front-plate barrier rib  26 . Specifically, the address electrode  12  may be positioned between the first barrier rib member  16   a  and the fifth barrier rib member  26   b , and may be shared by a pair of discharge cells  38  adjacent to the address electrode  12  in the second direction (the x-axis direction in the drawings). Successive address electrodes  12  are spaced with a predetermined distance therebetween.  
         [0049]     A first electrode  31 A and a second electrode  31 B extend in the second direction, while being electrically insulated from the address electrode  12 , and are arranged corresponding to the second barrier rib members  16   b . In the first embodiment, the first electrode  31 A and the second electrode  31 B are alternately disposed, and are arranged between the second barrier rib members  16   b  and the sixth barrier rib members  26   c . Thus, they can divide adjacent discharge cells  38 , and each first electrode  31 A and second electrode  31 B may be shared by adjacent discharge cells  38 .  
         [0050]     Furthermore, a scan electrode  32  is arranged between a first electrode  31 A and a second electrode  31 B and between the third barrier rib member  16   c  and the fourth barrier rib member  26   a . Thus, each discharge cell  38  may be divided into a first discharge space  38   a  between a first electrode  31 A and a scan electrode  32  and a second discharge space  38   b  between a second electrode  32 A and the scan electrode  32 . Therefore, a scan electrode  32  divides a discharge cell  38  into two discharge spaces  38   a  and  38   b.    
         [0051]     In the present embodiment, since the first electrode  31 A and the second electrode  31 B are shared by adjacent discharge cells  38  in the first direction, the first discharge spaces  38   a  of the adjacent discharge cells  38  are adjacent to each other and the second discharge spaces  38   b  of adjacent discharge cells  38  are adjacent to each other as shown in  FIG. 4 .  
         [0052]     An address electrode  12  is shared by the two adjacent discharge cells  38  in the second direction. Thus, to select a discharge cell  38  to be turned on, a protruding portion  121  extending into a discharge cell  38  is arranged on the address electrode  12 . The protruding portion  121  of the address electrode  12  applies a scan pulse, which is applied to the address electrode  12 , to a discharge cell  38 . Therefore, the protruding portion  121  causes the discharge cell  38  to be selected. Because protruding portion  121  shortens the discharge gap, the address discharge voltage is lowered.  
         [0053]     In the present embodiment, an address discharge can be generated in each first discharge space  38   a  formed between the first electrode  31 A and the scan electrode  32  and the second discharge space  38   b  formed between the second electrode  31 B and the scan electrode  32  within one discharge cell  38 . A protruding portion  121  of the address electrode  12  extends into a first discharge space  38   a  between the first electrode  31 A and the scan electrode  32 , and a protruding portion  121  of the address electrode  12  extends into a second discharge space  38   b  between the second electrode  31 B and the scan electrode  32 . Therefore, an address discharge can be generated in discharge spaces  38   a  and  38   b  arranged on two sides of scan electrode  32 .  
         [0054]     In the present embodiment, the first electrode  31 A and the second electrode  31 B participating in a sustain discharge and the scan electrode  32  are arranged opposite to each other and generate a sustain discharge as an opposed discharge. It is thus possible to lower a sustain discharge firing voltage.  
         [0055]     As shown in  FIG. 3 , the first electrode  31 A has an expansion portion  31 A 1 , the second electrode  31 B has an expansion portion  31 B 1 , and the scan electrode  32  has an expansion portion  321 . Expansion portions  31 A 1 ,  31 B 1 , and  321  extend in a direction vertical to the rear substrate  10  (a Z-axis direction of the drawings) at a portion corresponding to each discharge cell  38  to generate a sustain discharge as an opposed discharge over a wider area. An opposed discharge includes discharge between electrodes positioned at opposite sides of a discharge space or discharge cell. The expansion portions  31 A 1 ,  31 B 1 , and  321  have a sectional structure in which the height in a vertical direction (h v ) is greater than the width in a horizontal direction (h h ) taken along a section vertical to the second direction (the x-axis direction of the drawings). An opposed discharge between the wider expansion portions  31 A 1 ,  31 B 1 , and  321  generates strong VUV rays. The strong VUV rays increase the amount of visible light, which is generated through collision with the phosphor layers  19  and  29  across the wide area within the discharge cells  38 .  
         [0056]     Referring to  FIG. 3 , the first electrode  31 A and the second electrode  31 B and the scan electrode  32  have a uniform width along expansion portions  31 A 1 ,  31 B 1 , and  321  and can cross the address electrodes  12  with protruding portion  121  while remaining electrically insulated. Although this embodiment illustrates the first and second electrodes  31 A and  31 B and the scan electrode  32  with uniform line width, the present invention is not restricted thereto.  
         [0057]     Referring to  FIG. 2 , the distance (h 1 ) between the bottom of the protruding portion  121  of the address electrode  12  and the top portion of the rear substrate  10  is substantially the same as the distance (h 2 ) between the bottom of the first electrode  31 A, the bottom of the second electrode  31 B and the top portion of the rear substrate  10 , and substantially the same as the distance (h 3 ) between the bottom portion of the scan electrode  32  and the top portion of the rear substrate  10 . Thus, an opposed discharge can be generated between the scan electrode  32  and the protruding portion  121  of the address electrode  12 . In addition, the thickness (t 3 ) of the address electrode  12  in a vertical direction (the z-axis direction of the drawings) is less than the thickness (t 4 ) of the first electrode  31 A and the second electrode  31 B and the thickness (t 5 ) of the scan electrode  32 , thus preventing the address electrode  12  from obstructing a sustain discharge between the first electrode  31 A and the scan electrode  32 , and between the second electrode  31 B and the scan electrode  32 .  
         [0058]     Dielectric layers  34  and  35  are formed with an insulation structure while surrounding the first electrode  31 A, the second electrode  31 B, the scan electrode  32 , and the address electrode  12 . The dielectric layers  34  and  35  can be fabricated by a Thick Film Ceramic Sheet (TFCS) method. The first electrode  31 A, the second electrode  31 B, the scan electrode  32 , and the address electrode  12  can be fabricated by separately forming the dielectric layers  34  and  35 , the respective electrodes formed therein, and then combining them with the rear substrate  10  on which the rear-plate barrier rib  16  is formed.  
         [0059]     These dielectric layers  34  and  35  provide insulation between electrodes and also accumulate wall charges by discharge thereon. In the disclosed embodiment, the address electrode  12  is surrounded by the dielectric layer  35  having the same dielectric constant and can thus have the same discharge firing voltage in discharge cells, implementing red, green, and blue colors.  
         [0060]     An MgO protective layer  36  can be formed on surfaces of the dielectric layers  34  surrounding the first electrode  31 A, the second electrode  31 B, and the scan electrode  32 , and the dielectric layers  35  surrounding the address electrode  12 . More particularly, the MgO protective layer  36  can be formed at a portion of the dielectric layers  34  and  35  exposed to plasma discharge occurring in the discharge space within the discharge cells  38 . In the present embodiment, the first electrode  31 A, the second electrode  31 B, the scan electrode  32 , and the address electrode  12  are located at portions which have substantially less contribution to display between the rear substrate  10  and the front substrate  20 . Therefore, the MgO protective layer  36  coated on the dielectric layers  34  and  35  covering the first electrode  31 A, the second electrode  31 B, the scan electrode  32 , and the address electrode  12  can be comprised of MgO with a visible light non-transparent characteristic. Non-transparent MgO has a secondary electron emission coefficient value that is significantly higher than that of transparent MgO. Accordingly, it can further lower a discharge firing voltage.  
         [0061]      FIG. 4  shows a partial top plan view of the PDP according to the first embodiment of the present invention.  
         [0062]     Referring to  FIG. 4 , each discharge cell  38  is divided into two discharge spaces  38   a  and  38   b  by means of the scan electrode  32 , as described above. Scan electrodes  32  are coupled with scan lines Yn, Yn+ 1 , Yn+ 2 , Yn+ 3 , etc. First electrodes  31 A are coupled with sustain lines X 1 , and second electrodes  31 B are coupled with sustain lines X 2 . In a sustain period, a sustain discharge is generated between a first electrode  31 A and a scan electrode  32  in a first discharge space  38   a , and a sustain discharge is generated between a second electrode  31 B and a scan electrode  32  in a second discharge space  38   b . Since a discharge is generated between a scan electrode  32  that passes through a discharge cell  38 , and a first electrode  31 A and a second electrode  31 B arranged on opposite sides of a scan electrode  32 , a discharge gap between electrodes participating in sustain discharge can be significantly reduced. Consequently, a discharge firing voltage can be further lowered.  
         [0063]     Hereinafter, a method of driving the PDP in which each discharge cell  38  is divided into two discharge spaces  38   a  and  38   b  as described above will be described.  
         [0064]      FIG. 5  shows a driving waveform for illustrating a driving method of a PDP according to a second embodiment of the present invention, and  FIG. 6  shows a conceptual view showing the driving method of the PDP according to the second embodiment of the present invention. In this case, an odd line and an even line of  FIG. 6  correspond to one discharge space, respectively. One odd line and one even line correspond to one discharge cell.  
         [0065]     As shown in  FIG. 5 , each subfield of the driving method according to the present embodiment includes a reset period, an address period, and a sustain period. More particularly, the driving method according to the present embodiment includes a first address period (I), where one discharge space formed between a first electrode of a first sustain electrode group X 1  and the scan electrode Y is selected, and a second address period (II), where the other discharge space formed between a second electrode of a second sustain electrode group X 2  and the scan electrode Y is selected. Each discharge cell can be divided into two discharge spaces by a scan electrode Y.  
         [0066]     First, in the reset period, a voltage that gradually rises then gradually falls can be applied to the scan electrodes Y. The reset period sets up wall charges to perform a next address discharge stably while erasing a wall charge state of a previous sustain discharge. While the ramp voltage that gradually falls is applied to the scan electrodes Y, the first sustain electrode group X 1  and the second sustain electrode group X 2  are biased with a voltage (Ve) to generate a weak discharge from the first sustain electrode group X 1  and from the second sustain electrode group X 2  to the scan electrodes Y.  
         [0067]     Subsequently, in the address period, a discharge cell to be turned on is selected. In the present embodiment, the address period is divided into the first address period (I) and the second address period (II).  
         [0068]     In the first address period (I), while the first sustain electrode group X 1  is biased with voltage (Ve), a scan pulse voltage (Vsc) is sequentially applied to the scan electrodes Y 1  . . . Yn. During the first address period (I), the second sustain electrode group X 2  is not biased with voltage (Ve). Thus, a cell is selected by applying an address voltage (Va) to an address electrode A corresponding to a cell to be selected.  
         [0069]     Referring to  FIG. 6 , numerals written on the left of the drawing designate discharge spaces within the plasma display panel. In the first address period (I), only discharge spaces where the first sustain electrode group X 1  takes part in discharge (i.e., lines  1 ,  4 ,  5 ,  8 ,  9 , etc. of  FIG. 6 ). are addressed and thus selected. Since the voltage (Ve) is applied to only the first sustain electrode group X 1 , only discharge spaces where the first sustain electrode group X 1  takes part in discharge generate an address discharge and are thus selected. This will be described below in more detail.  
         [0070]     The voltage (Ve) applied to the first sustain electrode group X 1  generates discharge between the first sustain electrode group X 1  and the scan electrode Y at the initial stage of an address discharge, and attracts negative (−) wall charges generated in the address discharge toward the first sustain electrode group X 1  after the address discharge. Therefore, where only the first sustain electrode group X 1  is biased with the voltage (Ve) in the first address period (I), only a discharge space in which the first sustain electrode group X 1  will take part in discharge is addressed. In the second address period (II), only the second sustain electrodes of group X 2  are biased with the voltage (Ve). The scan pulse voltage (Vsc) is then sequentially applied to the scan electrodes Y 1  . . . Yn while the first sustain electrode group X 1  is not biased with voltage (Ve). Thus, a cell is selected by applying the address voltage (Va) to an address electrode  12  of a cell to be selected.  
         [0071]     Referring to  FIG. 6 , in the second address period (II), only a discharge space where the second sustain electrode group X 2  takes part in discharge is addressed or selected. Since the voltage (Ve) is applied to only the second sustain electrode group X 2 , discharge spaces (lines  2 ,  3 ,  6 ,  7 , etc. of  FIG. 6 ) where the second sustain electrode group X 2  participates in a discharge generate an address discharge and are addressed accordingly.  
         [0072]     Discharge spaces of each discharge cell, consisting of two discharge spaces, are all selected in the address period during the first address period (I) and the second address period (II).  
         [0073]     Meanwhile, in the sustain period after the first address period (I) and the second address period (II), a sustain discharge pulse voltage (Vs) is alternately applied to the scan electrodes Y and the first sustain electrode groups X 1  and second sustain electrode groups X 2  to display images on discharge spaces that have been addressed in the address period. Although the same voltage (Vs or 0V) is simultaneously applied to the first sustain electrode group X 1  and the second sustain electrode group X 2  in the sustain period, a sustain discharge is generated only in discharge spaces that have been addressed in the address period.  
         [0074]      FIG. 7  shows a driving waveform for illustrating a driving method of a PDP according to a third embodiment of the present invention.  FIG. 8  is a view conceptually showing the driving method of the PDP according to the third embodiment of the present invention. In  FIG. 8 , numerals written on the left of the drawing have the same meaning as in  FIG. 6 .  
         [0075]     Referring to  FIG. 7 , the driving waveform according to the third embodiment of the present invention has a first sustain period (I) occurring after only discharge spaces where the first sustain electrode group X 1  takes part in a discharge are selected in the first address period (I), and a second sustain period (II) occurring after only the discharge spaces  38   b  where the second sustain electrode group X 2  takes part in a discharge are selected in the second address period (II). In the first address period (I), only the first sustain electrode group X 1  is biased with the voltage (Ve), and the scan pulse voltage (Vsc) is sequentially applied to the scan electrodes (i.e., Y 1 , Y 2 , . . . Yn) in the same manner as in the second embodiment. Accordingly, only discharge spaces (lines  1 ,  4 ,  5 ,  8 ,  9 , etc. of  FIG. 8 ) where the first sustain electrode group X 1  takes part in a discharge are addressed. After, in the first sustain period (I), the sustain discharge pulse voltage (Vs) is alternately applied to the scan electrodes Y and the first sustain electrode group X 1 , so that sustain discharge is generated only in discharge spaces where the first sustain electrode group X 1  takes part in a discharge.  
         [0076]     Thereafter, in the second address period (II), only the second sustain electrode group X 2  is biased with the voltage (Ve), and the scan pulse voltage (Vsc) is sequentially applied to the scan electrodes Y (i.e., Y 1 , Y 2 , . . . Yn). Therefore, only discharge spaces (lines  2 ,  3 ,  6 ,  7 , etc. of  FIG. 8 ) where the second sustain electrode group X 2  takes part in a discharge are addressed. Subsequently, in the second sustain period (II), the sustain discharge pulse voltage (Vs) is alternately applied to the scan electrodes Y and the second sustain electrode group X 2 , so that sustain discharge is generated only in discharge spaces where the second sustain electrode group X 2  takes part in a discharge.  
         [0077]     In this embodiment, the number of sustain pulses applied in the first sustain period (I) and the second sustain period (II) are the number allocated by a weight value of a subfield, and are the same for the two discharge spaces in a discharge cell. In addition, in  FIG. 7  the sustain discharge pulse voltage (Vs) is not applied to the second sustain electrode group X 2  in the first sustain period (I), and the sustain discharge pulse voltage (Vs) is not applied to the first sustain electrode group X 1  in the second sustain period (II). However, the sustain discharge pulse voltage (Vs) can be applied to the second sustain electrode group X 2  in the first sustain period (I) and the first sustain electrode group X 1  in the second sustain period (II). This is because since only discharge spaces adjacent to the sustain electrode group X 1  are selected in the first address period (I), a sustain discharge is not generated although the sustain discharge pulse voltage (Vs) is applied to the second sustain electrode group X 2 .  
         [0078]     It will be apparent to those skilled in the art that various modifications and variation can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.