Patent Publication Number: US-6657397-B2

Title: Method for resetting a plasma display panel in address-while-display driving mode

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method for resetting a plasma display panel, and more particularly, to a method for resetting the state of discharge cells of each of XY-electrode line pairs while a surface discharge type triode plasma display panel is driven by an address-while-display driving method. 
     2. Description of the Related Art 
     FIG. 1 shows the structure of a surface discharge type triode plasma display panel. FIG. 2 shows an example of a discharge cell of the plasma display panel shown in FIG.  1 . Referring to FIGS. 1 and 2, address electrode lines A 1 , A 2 , . . . , A m−1 , A m , dielectric layers  11  and  15 , Y-electrode lines Y 1 , . . . , Y n , X-electrode lines X 1 , . . . , X n , phosphor layers  16 , partition walls  17 , and a magnesium oxide (MgO) layer  12  as a protective layer are provided between front and rear glass substrates  10  and  13  of a general surface discharge plasma display panel  1 . 
     The address electrode lines A 1  through A m  are formed on the front surface of the rear glass substrate  13  in a predetermined pattern. A rear dielectric layer  15  is formed on the entire surface of the rear glass substrate  13  having the address electrode lines A 1  through A m . The partition walls  17  are formed on the front surface of the rear dielectric layer  15  to be parallel to the address electrode lines A 1  through A m . These partition walls  17  define the discharge areas of respective discharge cells and serve to prevent cross talk between discharge cells. The phosphor layers  16  are deposited between partition walls  17 . 
     The X-electrode lines X 1  through X n  and the Y-electrode lines Y 1  through Y n  are formed on the rear surface of the front glass substrate  10  in a predetermined pattern to be orthogonal to the address electrode lines A 1  through A m . The respective intersections define discharge cells. Each of the X-electrode lines X 1  through X n  is composed of a transparent electrode line X na  (FIG. 2) formed of a transparent conductive material, e.g., indium tin oxide (ITO), and a metal electrode line X nb  (FIG. 2) for increasing conductivity. Each of the Y-electrode lines Y 1  through Y n  is composed of a transparent electrode line Y na  (FIG. 2) formed of a transparent conductive material, e.g., ITO, and a metal electrode line Y nb  (FIG. 2) for increasing conductivity. A front dielectric layer  11  is deposited on the entire rear surface of the front glass substrate  10  having the rear surfaces of the X-electrode lines X 1  through X n  and the Y-electrode lines Y 1  through Y n . The protective layer  12 , e.g., a MgO layer, for protecting the panel  1  against a strong electrical field is deposited on the entire surface of the front dielectric layer  11 . A gas for forming plasma is hermetically sealed in a discharge space  14 . 
     FIG. 3 shows a typical address-display separation driving method with respect to Y-electrode lines of the plasma display panel shown in FIG.  1 . Referring to FIG. 3, to realize time-division gray scale display, a unit frame is divided into 8 subfields SF 1  through SF 8 . In addition, the individual subfields SF 1  through SF 8  are composed of address periods A 1  through A 8 , respectively, and display periods S 1  through S 8 , respectively. 
     During each of the address periods A 1  through A 8 , display data signals are applied to the address electrode lines A 1  through A m  of FIG. 1, and simultaneously, a scan pulse is sequentially applied to the Y-electrode lines Y 1  through Y n . If a high-level display data signal is applied to some of the address electrode lines A 1  through A m  while the scan pulse is applied, wall charges are induced from address discharge only in relevant discharge cells. 
     During each of the display periods S 1  through S 8 , a display discharge pulse is alternately applied to the Y-electrode lines Y 1  through Y n  and the X-electrode lines X 1  through X n , thereby provoking display discharge in discharge cells in which wall charges are induced during each of the address periods A 1  through A 8 . Accordingly, the brightness of a plasma display panel is proportional to a total length of the display periods S 1  through S 8  in a unit frame. The total length of the display periods S 1  through S 8  in a unit frame is 255T (T is a unit time). Accordingly, including a case where the unit frame is not displayed, 256 gray scales can be displayed. 
     Here, the display period S 1  of the first subfield SF 1  is set to a time 1T corresponding to 2 0 . The display period S 2  of the second subfield SF 2  is set to a time 2T corresponding to 2 1 . The display period S 3  of the third subfield SF 3  is set to a time 4T corresponding to 2 2 . The display period S 4  of the fourth subfield SF 4  is set to a time 8T corresponding to 2 3 . The display period S 5  of the fifth subfield SF 5  is set to a time 16T corresponding to 2 4 . The display period S 6  of the sixth subfield SF 6  is set to a time 32T corresponding to 2 5 . The display period S 7  of the seventh subfield SF 7  is set to a time 64T corresponding to 2 6 . The display period S 8  of the eighth subfield SF 8  is set to a time 128T corresponding to 2 7 . 
     Accordingly, if a subfield to be displayed is appropriately selected from among 8 subfields, a total of 256 gray scales including a gray level of zero at which display is not performed in any subfield can be displayed. 
     According to the above-described address-display separation display method, the time domains of the respective subfields SF 1  through SF 8  are separated, so the time domains of respective address periods of the subfields SF 1  through SF 8  are separated, and the time domains of respective display periods of the subfields SF 1  through SF 8  are separated. Accordingly, during an address period, an XY-electrode line pair is kept waiting after being addressed until all of the other XY-electrode line pairs are addressed. Consequently, in each subfield, an address period increases, and a display period decreases. As a result, the brightness of light emitted from a plasma display panel decreases. A method proposed for overcoming this problem is an address-while-display driving method as shown in FIG.  4 . 
     FIG. 4 shows a typical address-while-display driving method with respect to the Y-electrode lines of the plasma display panel shown in FIG.  1 . Referring to FIG. 4, to realize time-division gray scale display, a unit frame is divided into 8 subfields SF 1  through SF 8 . Here, the subfields SF 1  through SF 8  overlap with respect to the Y-electrode lines Y 1  through Y n  and constitute a unit frame. Since all of the subfields SF 1  through SF 8  exist at any time point, address time slots are set among display discharge pulses in order to perform each address step. 
     In each of the subfields SF 1  through SF 8 , a reset step, address step, and display discharge step are performed. A time allocated to each of the subfields SF 1  through SF 8  depends on a display discharge time corresponding to a gray scale. For example, when displaying 256 gray scales with 8-bit video data in units of frames, if a unit frame (usually, {fraction (1/60)} second) is composed of 256 unit times, the first subfield SF 1  driven according to video data of the least significant bit has 1 (2 0 ) unit time, the second subfield SF 2  has 2 (2 1 ) unit times, the third subfield SF 3  has 4 (2 2 ) unit times, the fourth subfield SF 4  has 8 (2 3 ) unit times, the fifth subfield SF 5  has 16 (2 4 ) unit times, the sixth subfield SF 6  has 32 (2 5 ) unit times, the seventh subfield SF 7  has 64 (2 6 ) unit times, and the eighth subfield SF 8  driven according to video data of the most significant bit has 128 (2 7 ) unit times. Since the sum of unit times allocated to the subfields SF 1  through SF 8  is 255, 255 gray scale display can be accomplished. If a gray scale having no display discharge in any subfield is included, 256 gray scale display can be accomplished. 
     FIG. 5 shows a typical driving apparatus for the plasma display panel shown in FIG.  1 . Referring to FIG. 5, the typical driving apparatus for the plasma display panel  1  includes a video processor  66 , a logic controller  62 , an address driver  63 , an X-driver  64 , and a Y-driver  65 . The video processor  66  converts an external analog video signal into a digital signal to generate an internal video signal composed of, for example, 8-bit red (R) video data, 8-bit green (G) video data, 8-bit blue (B) video data, a clock signal, a horizontal synchronizing signal, and a vertical synchronizing signal. The logic controller  62  generates drive control signals S A , S Y , and S X  in response to the internal video signal from the video processor  66 . The address driver  63  processes the address signal S A  among the drive control signals S A , S Y , and S X  output from the logic controller  62  to generate a display data signal and applies the display data signal to address electrode lines. The X-driver processes the X-drive control signal S X  among the drive control signals S A , S Y , and S X  output from the logic controller  62  and applies the result of processing to X-electrode lines. The Y-driver processes the Y-drive control signal S Y  among the drive control signals S A , S Y , and S X  output from the logic controller  62  and applies the result of processing to Y-electrode lines. 
     When an address-while-display driving method as shown in FIG. 4 is applied to the above-described driving of a plasma display panel, the brightness of light emitted from the plasma display panel can be increased, but it is not easy to perform reset while display pulses are periodically applied, which causes resetting performance to fall off. 
     For example, in a resetting process according to a conventional address-while-display driving method, a simple erasure discharge in which wall charges are erased from only cells in which display discharges have occurred in a previous subfield occurs. Accordingly, while space charges increase in the cells in which display discharges have occurred in a previous subfield, space charge decrease in cells in which display discharges have not occurred in the previous subfield. In this case, while the cells in which display discharges have occurred in a previous subfield can be selected by a relatively lower address voltage, the cells in which display discharges have not occurred can be selected by a relatively higher address voltage. Accordingly, address voltage and display voltage must be increased, which may badly affect the reliability and life of a plasma display apparatus. Moreover, display brightness is not uniform among the cells in which display discharges have occurred in a previous subfield and the cells in which display discharges have not occurred in the previous subfield, thereby degrading the display performance. 
     SUMMARY OF THE INVENTION 
     To solve the above-described problems, it is an object of the present invention to provide a resetting method capable of demonstrating high performance in driving a surface discharge type triode plasma display panel using an address-while-display driving method so that display performance can be increased and that address voltage and display voltage can be decreased, thereby improving the reliability and life of a plasma display apparatus. 
     To achieve the above object of the present invention, there is provided a resetting method for uniforming the state of discharge cells of each of XY-electrode line pairs while a positive voltage of a first level and a negative voltage of the first level are alternately applied to all X- and Y-electrode lines of a surface discharge type triode plasma display panel. The resetting method includes a line discharge step, an erasure step, and an iteration step. 
     The line discharge step is performed during a part of a first pulse width period during which the negative voltage of the first level is applied to all of the X-electrode lines, and simultaneously, the positive voltage of the first level is applied to all of the Y-electrode lines, since a second subfield corresponding to the first XY-electrode line pair starts after a first subfield corresponding to the first XY-electrode line pair ends. In the line discharge step, a negative voltage of a second level higher than the first level is applied to an X-electrode line of the first XY-electrode line pair, and simultaneously, a positive voltage of a third level higher than the first level is applied to a Y-electrode line of the first XY-electrode line pair, thereby provoking discharges in all discharge cells corresponding to the first XY-electrode line pair. In the erasure step, wall charges are erased from all of the discharge cells corresponding to the first XY-electrode line pair. In the iteration step, the line discharge step and the erasure step are repeated on the remaining XY-electrode line pairs. 
     According to the resetting method of the present invention, in the line discharge step, due to application of the negative voltage of the second level higher than the first level and the positive voltage of the third level higher than the first level, discharges are provoked in all of the discharge cells corresponding to the first XY-electrode line pair so that wall charges and space charges are satisfactorily formed. In the next erasure step, the wall charges are uniformly erased from all of the discharge cells corresponding to the first XY-electrode line pair, but the space charges still satisfactorily remain. Moreover, since the iteration step is performed, the line discharge step and the erasure step can be performed on each of the remaining XY-electrode line pairs while the positive voltage of the first level and the negative voltage of the first level are alternately applied to all of the X- and Y-electrode lines. As described above, since effective resetting adequate for an address-while-display driving method is performed, display performance increases. In addition, an address voltage and a display voltage are set to be low, thereby improving the reliability and the life of a plasma display apparatus. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above object and advantages of the present invention will become more apparent by describing in detail preferred embodiments thereof with reference to the attached drawings. 
     FIG. 1 is a perspective view of the internal structure of a typical surface discharge type triode plasma display panel. 
     FIG. 2 is a sectional view of an example of a discharge cell in the plasma display panel shown in FIG.  1 . 
     FIG. 3 is a timing chart of a typical address-display separation driving method with respect to Y-electrode lines of the plasma display panel shown in FIG.  1 . 
     FIG. 4 is a timing chart of a typical address-while-display driving method with respect to Y-electrode lines of the plasma display panel shown in FIG.  1 . 
     FIG. 5 is a block diagram of a typical driving apparatus for the plasma display panel shown in FIG.  1 . 
     FIG. 6 is a timing chart of a resetting method used for an address-while-display driving method according to a first embodiment of the present invention. 
     FIG. 7 is a circuit diagram of X- and Y-drivers which can perform the resetting method of FIG.  6 . 
     FIG. 8 is a timing chart of a resetting method used for an address-while-display driving method according to a second embodiment of the present invention. 
     FIG. 9 is a circuit diagram of X- and Y-drivers which can perform the resetting method of FIG.  8 . 
     FIG. 10 is a timing chart of a resetting method used for an address-while-display driving method according to a third embodiment of the present invention. 
     FIG. 11 is a circuit diagram of X- and Y-drivers which can perform the resetting method of FIG.  10 . 
     FIG. 12 is a timing chart of a resetting method used for an address-while-display driving method according to a fourth embodiment of the present invention. 
     FIG. 13 is a circuit diagram of X- and Y-drivers which can perform the resetting method of FIG.  12 . 
     FIG. 14 is a graph of display voltages applied to a discharge cell versus address voltages applied thereto when a resetting method according to the present invention is used. 
     FIG. 15 is a graph of display voltages applied to a discharge cell versus address voltages applied thereto when a conventional simple resetting method is used. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 6 shows a resetting method used for an address-while-display driving method according to a first embodiment of the present invention. In FIG. 6, a reference character S X1  denotes a driving signal applied to an X-electrode line of an XY-electrode line pair performing initial resetting and addressing in a unit frame FR 1 , and a reference character S Y1  denotes a driving signal applied to the Y-electrode line of the XY-electrode line pair performing the initial resetting and addressing in the unit frame FR 1 . A reference character S X2  denotes a driving signal applied to an X-electrode line of an XY-electrode line pair performing second resetting and addressing in the unit frame FR 1 , and a reference character S Y2  denotes a driving signal applied to the Y-electrode line of the XY-electrode line pair performing the second resetting and addressing in the unit frame FR 1 . A reference character S Xn  denotes a driving signal applied to an X-electrode line of an XY-electrode line pair performing last resetting and addressing in the unit frame FR 1 , and a reference character S Yn  denotes a driving signal applied to the Y-electrode line of the XY-electrode line pair performing the last resetting and addressing in the unit frame FR 1 . A reference character S A1 . . . m  denotes a display data signal applied from the address driver  63  of FIG. 5 to all address electrode lines. 
     FIG. 7 shows X- and Y-drivers which can perform the resetting method of FIG.  6 . In FIG. 7, a circuit on the left of the plasma display panel  1  corresponds to the Y-driver  65  of FIG. 5, and a circuit on the right of the plasma display panel  1  corresponds to the X-driver  64  of FIG.  5 . 
     Referring to FIG. 7, the Y-driver ( 65  of FIG. 5) includes upper transistors YU 1  through YU n , lower transistors YL 1  through YL n , a Y-energy regeneration circuit ER Y , a Y-display discharge circuit SP Y , and a Y-resetting/addressing circuit RA. The upper transistors YU 1  through YU n  and the lower transistors YL 1  through YL n  are connected to Y-electrode lines Y 1  through Y n . The Y-energy regeneration circuit ER Y  collects charges around the Y-electrode lines Y 1  through Y n  during the falling time of display discharge pulses simultaneously applied from the Y-display discharge circuit SP Y  to the Y-electrode lines Y 1  through Y n  and applies the collected charges to the Y-electrode lines Y 1  through Y n  during the rising time of the display discharge pulses. The Y-display discharge circuit SP Y  alternately applies a positive voltage Vpb of a first level and a negative voltage Vsl of the first level to the Y-electrode lines Y 1  through Y n . The Y-energy regeneration circuit ER Y  and the Y-display discharge circuit SP Y  are commonly applied to all of the Y-electrode lines Y 1  through Y n  through the upper transistors YU 1  through YU n . The Y-resetting/addressing circuit RA outputs voltages Vre and Vel for resetting according to the present invention and a voltage Vsc for addressing during resetting time and addressing time for each Y-electrode line. Accordingly, the Y-resetting/addressing circuit RA is independently applied to each of the Y-electrode lines Y 1  through Y n  through each of the lower transistors YL 1  through YL n . 
     Similarly, the X-driver ( 64  of FIG. 5) includes upper transistors XU 1  through XU n , lower transistors XL 1  through XL n , an X-energy regeneration circuit ER x , an X-display discharge circuit SP X , and an X-resetting circuit RE. The upper transistors XU 1  through XU n  and the lower transistors XL 1  through XL n  are connected to X-electrode lines X 1  through X n . The X-energy regeneration circuit ER X  collects charges around the X-electrode lines X 1  through X n  during the falling time of display discharge pulses simultaneously applied from the X-display discharge circuit SP X  to the X-electrode lines X 1  through X n  and applies the collected charges to the X-electrode lines X 1  through X n  during the rising time of the display discharge pulses. The X-display discharge circuit SP X  alternately applies a positive voltage Vpb of a first level and a negative voltage Vsl of the first level to the X-electrode lines X 1  through X n . The X-energy regeneration circuit ER X  and the X-display discharge circuit SP X  are commonly applied to all of the X-electrode lines X 1  through X n  through the upper transistors XU 1  through XU n . The X-resetting circuit RE outputs voltages Veh and Vsc for resetting according to the present invention during resetting time for each X-electrode line. Accordingly, the X-resetting circuit RE is independently applied to each of the X-electrode lines X 1  through X n  through each of the lower transistors XL 1  through XL n . 
     A resetting method according to the present invention used for an address-while-display driving method will be described in detail with reference to FIGS. 6 and 7. 
     As shown in FIG. 6, in an address-while-display driving method for a plasma display panel, resetting and addressing are performed on the XY-electrode line pairs X 1 Y 1 , X 2 Y 2 , . . . , X n Y n  while the positive and negative voltages Vpb and Vsl of the first level are alternately applied to all of the X- and Y-electrode lines X 1  through X n  and Y 1  through Y n . 
     A resetting method according to the present invention includes a line discharge step ta-t 1 , an erasure step tb-tc, and iteration steps. Since a second subfield corresponding to a first XY-electrode line pair starts after a first subfield corresponding to the first XY-electrode line pair performing initial resetting and addressing in a unit frame FR 1 , during a first pulse width period t 0 -t 1 , a negative voltage Vsl of a first level is applied to all of the X-electrode lines X 1  through X n , and simultaneously, a positive voltage Vpb of the first level is applied to all of the Y-electrode lines Y 1  through Y n . In the line discharge step ta-t 1  during the first pulse width period t 0 -t 1 , the upper transistors (for example, XU 1  and YU 1 ) of the first XY-electrode line pair (for example, X 1 Y 1 ) are turned off, the lower transistors (for example, XL 1  and YL 1 ) thereof are turned on, a transistor ST 13  of the X-resetting circuit RE is turned on, and a transistor ST 5  of the Y-resetting/addressing circuit RA is turned on. As a result, a negative voltage Vsc of a second level higher than the first level is applied to the X-electrode line X 1  of the first XY-electrode line pair X 1 Y 1 , and simultaneously, a positive voltage Vre of a third level higher than the first level is applied to the Y-electrode line Y 1  of the first XY-electrode line pair X 1 Y 1 . Accordingly, discharges are provoked in all discharge cells corresponding to the first XY-electrode line pair X 1 Y 1 , thereby uniformly forming wall charges and satisfactorily forming space charges. 
     During a second pulse width period t 1 -t 2  immediately after the first pulse width period t 0 -t 1  during which the line discharge step ta-t 1  is performed, the upper transistors XU 1  and YU 1  of the first XY-electrode line pair X 1 Y 1  are turned on, the lower transistors XL 1  and YL 1  thereof are turned off, a transistor ST 10  of the X-display discharge circuit SP X  is turned on, and a transistor ST 4  of the Y-display discharge circuit SP Y  is turned on. As a result, the positive voltage Vpb of the first level is applied to all of the X-electrode lines X 1  through X n , and simultaneously, the negative voltage Vsl of the first level is applied to all of the Y-electrode lines Y 1  through Y n , so that wall charges are uniformly formed and space charges are satisfactorily formed in all of the discharge cells corresponding to the first XY-electrode line pair X 1 Y 1 . 
     In an erasure step performed for a predetermined time tb-tc during a third pulse width period t 2 -t 3  immediately after the second pulse width period t 1 -t 2 , the upper transistors XU 1  and YU 1  of the first XY-electrode line pair X 1 Y 1  are turned off, the lower transistors XL 1  and YL 1  thereof are turned on, a transistor ST 12  of the X-resetting circuit RE is turned on, and a transistor ST 7  of the Y-resetting/addressing circuit RA is turned on. As a result, a positive voltage Veh of a fourth level lower than the first level is applied to the X-electrode line X 1  of the first XY-electrode line pair X 1 Y 1 , and simultaneously, a negative voltage Vel of a fifth level lower than the first level is applied to the Y-electrode line Y 1  of the first XY-electrode line pair X 1 Y 1 . Accordingly, wall charges are erased from all of the discharge cells corresponding to the first XY-electrode line pair X 1 Y 1 . However, the space charges satisfactorily remain in the discharge cells. 
     Such line discharge step and erasure step are sequentially performed on each of the remaining XY-electrode line pairs (see driving signals S X2  and S Y2  of FIG.  6 ). 
     According to a resetting method of the present invention as described referring to FIGS. 6 and 7, in the line discharge step ta-t 1 , discharges are provoked in all discharge cells corresponding to the first XY-electrode line pair X 1 Y 1  so that wall charges are uniformly formed and space charges are satisfactorily formed. In addition, since the second pulse width period t 1 -t 2  is immediately followed by the third pulse width period t 2 -t 3 , secondary discharges are provoked in all of the discharge cells corresponding to the first XY-electrode line pair X 1 Y 1  so that wall charges are more uniformly formed and space charges are more satisfactorily formed. In the next erasure step, the wall charges are uniformly erased from all of the discharge cells corresponding to the first XY-electrode line pair X 1 Y 1 , but the space charges still satisfactorily remain. Moreover, since the iteration step is performed, the line discharge step and the erasure step can be performed on each of the remaining XY-electrode line pairs while the positive voltage Vpb of the first level and the negative voltage Vsl of the first level are alternately applied to all of the X- and Y-electrode lines X 1  through X n  and Y 1  through Y n . As described above, effective and adequate resetting for an address-while-display driving method increases display performance. In addition, an address voltage and a display voltage are set to be low, thereby improving the reliability and the life of a plasma display apparatus. 
     In FIG. 6, durations td-te, th-ti, and ty-tz are for addressing during which wall charges are formed in selected discharge cells, after resetting according to the present invention. 
     FIG. 8 shows a resetting method used for an address-while-display driving method according to a second embodiment of the present invention. FIG. 9 shows X- and Y-drivers ( 64  and  65  of FIG. 5) which can perform the resetting method of FIG.  8 . In FIGS. 6 through 9, the same, reference characters denote the same members having the same functions. The second embodiment shown in FIGS. 8 and 9 is almost the same as the first embodiment shown in FIGS. 6 and 7 but has a difference in an erasure step. Thus, a description of the second embodiment shown in FIGS. 8 and 9 will be concentrated on an erasure step. 
     During the first half tb-tbc of an erasure time tb-tc, the upper transistors (for example, XU 1  and YU 1 ) of a first XY-electrode line pair (for example, X 1 Y 1 ) are turned off, the lower transistors (for example, XL 1  and YL 1 ) thereof are turned on, a transistor ST 12  of an X-resetting circuit RE is turned on, a transistor ST 7  of a Y-resetting/addressing circuit RA is turned on, and a positive voltage Va of a sixth level lower than the first level is applied to all of the address electrode lines A 1  through A m  of FIG.  1 . In other words, during the first half tb-tbc of an erasure time tb-tc, the negative voltage Vel of the fifth level lower than the first level is applied to the Y-electrode line Y 1  of the first XY-electrode line pair X 1 Y 1 , and simultaneously, the positive voltage Va of the sixth level lower than the first level is applied to all of the address electrode lines A 1  through A m . As a result, opposite discharges occur among the Y-electrode line Y 1  of the first XY-electrode line pair X 1 Y 1  and all of the address electrode lines A 1  through A m , thereby erasing wall charges which have been formed in all discharge cell corresponding to the first XY-electrode line pair X 1 Y 1 . Such erasure operation is repeated in each (for example, an erasure time tf-tg) of the following erasure times. 
     FIG. 10 shows a resetting method used for an address-while-display driving method according to a third embodiment of the present invention. FIG. 11 shows X- and Y-drivers ( 64  and  65  of FIG. 5) which can perform the resetting method of FIG.  10 . In FIGS. 6,  7 ,  10 , and  11 , the same reference characters denote the same members having the same functions. The third embodiment shown in FIGS. 10 and 11 is almost the same as the first embodiment shown in FIGS. 6 and 7 but has a difference in an erasure step. Thus, a description of the third embodiment shown in FIGS. 10 and 11 will be concentrated on an erasure step. 
     In the third embodiment, erasing is performed throughout a unit pulse width period t 2 -t 3 . During the time t 2 -t 3 , the upper transistor YU 1  of the Y-electrode line Y 1  of a first XY-electrode line pair (for example, X 1 Y 1 ) is turned off, the lower transistor YL 1  of the Y-electrode line Y 1  is turned on, and a transistor ST 15  of a Y-resetting/addressing circuit RA is turned on. As a result, according to the resistance value of a resistance device R connected to the source of the transistor ST 15 , a voltage applied to the Y-electrode line Y 1  of the first XY-electrode line pair X 1 Y 1  gradually increases from the negative voltage Vsl of the first level or a ground voltage GND to the positive voltage Vpb of the first level. Consequently, wall charges which have been formed in all discharge cells corresponding to the first XY-electrode line pair X 1 Y 1  are erased. Here, if the positive voltage Vre of the third level higher than the first level is applied to the drain of the transistor ST 15  of the Y-resetting/addressing circuit RA, a voltage applied to the Y-electrode line Y 1  of the first XY-electrode line pair X 1 Y 1  gradually increases from the negative voltage Vsl of the first level or the ground voltage GND to the positive voltage Vre of the third level according to the resistance value of the resistance device R connected to the source of the transistor ST 15 , thereby erasing wall charges which have been formed in all discharge cells corresponding to the first XY-electrode line pair X 1 Y 1 . 
     FIG. 12 shows a resetting method used for an address-while-display driving method according to a fourth embodiment of the present invention. FIG. 13 shows X- and Y-drivers ( 64  and  65  of FIG. 5) which can perform the resetting method of FIG.  12 . In FIGS. 6,  7 ,  12 , and  13 , the same reference characters denote the same members having the same functions. The fourth embodiment shown in FIGS. 12 and 13 is almost the same as the first embodiment shown in FIGS. 6 and 7 but has a difference in an erasure step. Thus, a description of the fourth embodiment shown in FIGS. 12 and 13 will be concentrated on an erasure step. 
     In the fourth embodiment, erasing is performed throughout a unit pulse width period t 2 -t 3 . During the time t 2 -t 3 , the upper transistor XU 1  of the X-electrode line X 1  of a first XY-electrode line pair (for example, X 1 Y 1 ) is turned off, the lower transistor XL 1  of the X-electrode line X 1  is turned on, and a transistor ST 16  of an X-resetting circuit RE is turned on. As a result, according to the resistance value of a resistance device R connected to the drain of the transistor ST 16 , a voltage applied to the X-electrode line X 1  of the first XY-electrode line pair X 1 Y 1  gradually decreases from the positive voltage Vpb of the first level or a ground voltage GND to the negative voltage Vsl of the first level. Consequently, wall charges which have been formed in all discharge cells corresponding to the first XY-electrode line pair X 1 Y 1  are erased. Here, if the negative voltage Vsc of the second level higher than the first level is applied to the source of the transistor ST 16  of the X-resetting circuit RE, a voltage applied to the X-electrode line X 1  of the first XY-electrode line pair X 1 Y 1  gradually decreases from the positive voltage Vpb of the first level or the ground voltage GND to the negative voltage Vsc of the second level according to the resistance value of the resistance device R connected to the drain of the transistor ST 16 , thereby erasing wall charges which have been formed in all discharge cells corresponding to the first XY-electrode line pair X 1 Y 1 . 
     FIG. 14 shows display voltages applied to a discharge cell versus address voltages applied thereto when a resetting method according to the present invention is used. FIG. 15 shows display voltages applied to a discharge cell versus address voltages applied thereto when a conventional simple resetting method is used. In FIGS. 14 and 15, a reference character Va denotes an address voltage applied between the address electrode of one discharge cell and the Y-electrode of the discharge cell or an address voltage applied between the address electrode of one discharge cell and the X-electrode of the discharge cell. Vs denotes a display voltage applied between the X-electrode and the Y-electrode of the discharge cell. Vaymax denotes a maximum address voltage with respect to each display voltage Vs when a Y-electrode is used as a scan electrode. Vaxmax denotes a maximum address voltage with respect to each display voltage Vs when an X-electrode is used as a scan electrode. Vaymin denotes a minimum address voltage with respect to each display voltage Vs when a Y-electrode is used as a scan electrode. Vaxmin denotes a minimum address voltage with respect to each display voltage Vs when an X-electrode is used as a scan electrode. Cpx denotes a graph of an overlap characteristic between the maximum address voltages Vaymax and Vaxmax according to the present invention. Cpn denotes a graph of an overlap characteristic between the minimum address voltages Vaymin and Vaxmin according to the present invention. Cox denotes a graph of an overlap characteristic between the maximum address voltages Vaymax and Vaxmax according to conventional technology. Cony denotes a characteristic graph of a minimum address voltage Vaymin according to conventional technology, when a Y-electrode is used as a scan electrode. Conx denotes a characteristic graph of a minimum address voltage Vaxmin according to conventional technology when an X-electrode is used as a scan electrode. Referring to FIGS. 14 and 15, the minimum address voltages Vaymin and Vaxmin according to the present invention are lower than those according to the conventional technology, so the margin of the address voltage Va increases. Particularly, in the present invention, even if the display voltage Vs decreases, the minimum address voltages Vaymin and Vaxmin do not increase. Here, the margin of the address voltage Va indicates a difference between a maximum address voltage and a minimum address voltage. 
     As described above, according to a resetting method of the present invention, discharges are provoked in all discharge cells corresponding to a first XY-electrode line pair in a line discharge step so that wall charges and space charges can satisfactorily formed. Accordingly, if an erasure step is performed, wall charges are uniformly erased from the all of the discharge cells corresponding to the first XY-electrode line pair, and space charges satisfactorily remain in the discharge cells. In addition, an iteration step enables the line discharge step and the erasure step on each of the XY-electrode line pairs while a positive voltage and a negative voltage are alternately applied to all X- and Y-electrode lines. Such effective resetting adequate for an address-while-display driving method enhances display performance. Moreover, a low address voltage and a low display voltage improve the reliability and the life of plasma display panel device. 
     The present invention is not restricted to the above-described embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.