Abstract:
A driving circuit for producing sustain waveforms of a plasma display panel (PDP) is mentioned. The driving circuit includes the functions of voltage clamping and energy recovery. By controlling switches contained in the driving circuit, the supplied voltage source can be made to be only half of the sustain voltage. The voltage stress of some components will therefore be lower. In addition, the numbers of components can be reduced in the driving circuit.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of the filing date of U.S. provisional patent application No. 60/595,304, filed Jun. 22, 2005, the contents of which are hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a driving circuit, and more specifically, to a driving circuit for a plasma display panel (PDP).  
         [0004]     2. Description of the Prior Art  
         [0005]     In recent years, there has been an increasing demand for planar displays such as plasma display panels (PDP), liquid-crystal displays (LCD) and electroluminescent displays (EL display) in place of cathode ray tube terminals (CRT) due to the advantage of the thin appearance of the planar displays.  
         [0006]     In a PDP display, charges are accumulated according to display data, and a sustaining discharge pulse is applied to paired electrodes in order to generate discharge glow for display. As far as the PDP display is concerned, it is required to apply a high voltage to the electrodes. In particular, a pulse-duration of several microseconds is usually adopted. Hence the power consumption of the PDP display is quite considerable. Energy recovering (power saving) is therefore sought for. Many designs and patents have been developed for providing methods and apparatuses of energy recovering for PDPs. One of the examples is U.S. Pat. No. 5,828,353 , “Drive Unit for Planar Display ” by Kishi, et al., which is included herein by reference.  
         [0007]     Please refer to  FIG. 1 .  FIG. 1  is a block diagram of a prior art plasma panel display driving circuit  100 . An equivalent capacitor of a plasma display panel is marked as Cp. The conventional driving circuit  100  includes four switches S 1  to S 4  for passing current, an X-side energy recovery circuit  110  and a Y-side energy recovery circuit  120  for charging/discharging the panel equivalent capacitor Cp from the X side of the panel equivalent capacitor Cp and the Y side of the panel equivalent capacitor Cp respectively. S 5 , S 6 , S 7  and S 8  are switches for passing current. D 5 , D 6 , D 7  and D 8  are diodes. V 1  and V 2  are two voltage sources. C 1  and C 2  are capacitors adopted for recovering energy, and L 1  and L 2  are resonant inductors. The X-side energy recovery circuit  110  includes an energy-forward channel comprising the switch S 6 , the diode D 6  and the inductor L 1 , and an energy-backward channel comprising the inductor L 1 , the diode D 5  and the switch S 5 . Similarly, the Y-side energy recovery circuit  120  also includes an energy-forward channel comprising the switch S 8 , the diode D 8  and the inductor L 2 , and an energy-backward channel comprising the inductor L 2 , the diode D 7  and the switch S 7 .  
         [0008]     Please refer to  FIG. 2 .  FIG. 2  is a flowchart of generating the sustaining pulses of the equivalent panel equivalent capacitor Cp of the PDP by the conventional driving circuit  100  illustrated in  FIG. 1 .  
         [0009]     Step  200 : Start;  
         [0010]     Step  210 : Keep the voltage potentials at the X side and the Y side of the panel equivalent capacitor Cp at ground by turning on the switches S 3  and S 4 ;  
         [0011]     Step  220 : Charge the X side of the panel equivalent capacitor Cp by the capacitor C 1  and keep the voltage potential at the Y side of the panel equivalent capacitor Cp at ground by turning on the switches S 6  and S 4 ; wherein the voltage potential at the X side of the panel equivalent capacitor Cp goes up to V 1  accordingly;  
         [0012]     Step  230 : Supply charge to the equivalent panel equivalent capacitor Cp of the PDP from the X side by turning on the switches S 1  and S 4 ; wherein the voltage potential at the X side of the panel equivalent capacitor Cp keeps at V 1  and the voltage potential at the Y side of the panel equivalent capacitor Cp keeps at ground accordingly;  
         [0013]     Step  240 : Discharge the panel equivalent capacitor Cp from the X side and keep the voltage potential at the Y side of the panel equivalent capacitor Cp at ground by turning on the switches S 5  and S 4 ; wherein the voltage potential at the X side of the panel equivalent capacitor Cp goes down to ground accordingly;  
         [0014]     Step  250 : Keep the voltage potentials at the X side and the Y side of the panel equivalent capacitor Cp at ground by turning on the switches S 3  and S 4 ;  
         [0015]     Step  260 : Charge the Y side of the panel equivalent capacitor Cp by the capacitor C 2  and keep the voltage potential at the X side of the panel equivalent capacitor Cp at ground by turning on the switches S 8  and S 3 ; wherein the voltage potential at the Y side of the panel equivalent capacitor Cp goes up to V 2  accordingly;  
         [0016]     Step  270 : Supply charge to the equivalent panel equivalent capacitor Cp of the PDP from the Y side by turning on the switches S 2  and S 3 ; wherein the voltage potential at the Y side of the panel equivalent capacitor Cp keeps at V 2  and the voltage potential at the X side of the panel equivalent capacitor Cp keeps at ground accordingly;  
         [0017]     Step  280 : Discharge the panel equivalent capacitor Cp from the Y side and keep the voltage potential at the X side of the panel equivalent capacitor Cp at ground by turning on the switches S 7  and S 3 ; wherein the voltage potential at the Y side of the panel equivalent capacitor Cp goes down to ground accordingly;  
         [0018]     Step  290 : Keep the voltage potentials at the X side and the Y side of the panel equivalent capacitor Cp at ground by turning on the switches S 3  and S 4 ;  
         [0019]     Step  295 : End.  
         [0020]     Please refer to  FIG. 3 .  FIG. 3  shows a diagram illustrating the voltage potentials at the X side and the Y side of the panel equivalent capacitor Cp, and the control signals, M 1  to M 8 , of the switches S 1  to S 8  in  FIG. 1  respectively. In  FIG. 3 , the horizontal axis represents the time, while the vertical axis represents the voltage potential. Note that the switches S 1  to S 8  are designed to close (turned on) for passing current when the control signal is high, and to open (turned off) such that no current can pass when the control signal is low.  
         [0021]     Conventionally, the energy recovery (power saving) circuit provides two individual channels of charging and discharging the equivalent capacitor respectively (energy-forward channel and energy-backward channel) for each side of the equivalent panel equivalent capacitor Cp. Therefore, the amount of required components is quite large. Furthermore, the circuit area of capacitors C 1  and C 2  is usually considerable. Hence the cost of energy recovery circuit is not easy to reduce.  
       SUMMARY OF THE INVENTION  
       [0022]     It is therefore an objective of the invention to provide plasma display panel driving circuits that solve the problems of the prior art.  
         [0023]     According to a preferred embodiment of the present invention, a claimed plasma display panel driving circuit includes a panel capacitor a first side and a second side; a first switch electrically connected between the first side of the panel capacitor and a first voltage; a first inductor and a second switch electrically connected in series between the first side of the panel capacitor and a first node; a third switch electrically connected between the first side of the panel capacitor and the first node; a fourth switch electrically connected between the first node and a second voltage; a fifth switch electrically connected between the second voltage and a second node; a first capacitor electrically connected between the first node and the second node; a sixth switch electrically connected between the second node and the third voltage; a seventh switch electrically connected between the second side of the panel capacitor and a fourth voltage; a second inductor and an eighth switch electrically connected in series between the second side of the panel capacitor and a third node; a ninth switch electrically connected between the second side of the panel capacitor and the third node; a tenth switch electrically connected between the third node and a fifth voltage; an eleventh switch electrically connected between the fifth voltage and a fourth node; a second capacitor electrically connected between the third node and the fourth node; and a twelfth switch electrically connected between the fourth node and the sixth voltage.  
         [0024]     According to another preferred embodiment of the present invention, a claimed plasma display panel driving circuit includes a panel capacitor having a first side and a second side; a first switch electrically connected between the first side of the panel capacitor and a first voltage; a second switch electrically connected between the second side of the panel capacitor and a second voltage; a third switch electrically connected between the second side of the panel capacitor and a first node; a fourth switch and a first inductor electrically connected in series between the second side of the panel capacitor and the first node; a fifth switch and a second inductor electrically connected in series between the first side of the panel capacitor and the first node; a sixth switch electrically connected between the first side of the panel capacitor and the first node; a seventh switch electrically connected between the first node and a third voltage; an eighth switch electrically connected between the third voltage and a second node; a capacitor electrically connected between the first node and the second node; and a ninth switch electrically connected between the second node and a fourth voltage.  
         [0025]     According to yet another preferred embodiment of the present invention, a claimed plasma display panel driving circuit includes a panel capacitor having a first side and a second side; a first switch electrically connected between the first side of the panel capacitor and a first voltage; a second switch electrically connected between the second side of the panel capacitor and a second voltage; a third switch electrically connected between the first side of the panel capacitor and a first node; a fourth switch electrically connected between the second side of the panel capacitor and the first node; an inductor electrically connected between the first node and a second node; a fifth switch electrically connected between the first node and the second node; a sixth switch electrically connected between the second node and a third voltage; a seventh switch electrically connected between the third voltage and a third node; a capacitor electrically connected between the second node and the third node; and an eighth switch electrically connected between the third node and a fourth voltage.  
         [0026]     It is an advantage that the voltage potential output by the voltage sources is only half of the sustaining voltage produced by the driving circuit. The voltage stress of some components in the driving circuit will therefore be lower. In addition, the numbers of components can be reduced in the driving circuit.  
         [0027]     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]      FIG. 1  is a driving circuit diagram of a prior art energy recovery circuit with an equivalent capacitor of a PDP.  
         [0029]      FIG. 2  is a flowchart of a prior art method of generating the sustaining pulses of the equivalent panel equivalent capacitor Cp.  
         [0030]      FIG. 3  is a diagram illustrating the voltage potentials at sides of the panel equivalent capacitor Cp and the control signals of the switches.  
         [0031]      FIG. 4  shows a circuit diagram of a plasma display panel driving circuit according to a first embodiment of the present invention.  
         [0032]      FIG. 5  is shows a circuit diagram of a plasma display panel driving circuit according to a second embodiment of the present invention.  
         [0033]      FIG. 6  is a flowchart illustrating the operation of the driving circuit of the second embodiment for creating a sustain waveform.  
         [0034]      FIG. 7  shows a circuit diagram of a plasma display panel driving circuit according to a third embodiment of the present invention.  
         [0035]      FIG. 8  is shows a circuit diagram of a plasma display panel driving circuit according to a fourth embodiment of the present invention.  
         [0036]      FIG. 9  is a flowchart illustrating the operation of the driving circuit of the fourth embodiment for creating a sustain waveform.  
         [0037]      FIG. 10  shows a circuit diagram of a plasma display panel driving circuit according to a fifth embodiment of the present invention.  
         [0038]      FIG. 11  is a flowchart illustrating the operation of the driving circuit of the fifth embodiment for creating a sustain waveform.  
         [0039]      FIG. 12  is shows a circuit diagram of a plasma display panel driving circuit according to a sixth embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0040]     The present invention provides plasma display panel driving circuits that allow the supplied voltage to be just half of the produced sustaining voltage. The advantages of this invention are that the supplied voltage will be around half of that of the prior art. The voltage stress of some components will therefore be lower. In addition, the numbers of components can be reduced in the driving circuits.  
         [0041]     Please refer to  FIG. 4 .  FIG. 4  shows a circuit diagram of a plasma display panel driving circuit  400  according to a first embodiment of the present invention. The driving circuit  400  is shown having an equivalent panel equivalent capacitor Cp of the PDP, and has an X side and a Y side. The driving circuit  400  comprises switches S 21  to S 30 , S 240 , and S 290 , capacitors C 21  and C 22 , inductors L 21  and L 22 , and voltage sources V 21  to V 26 . Switches S 240  and S 290  are unidirectional switches, and the direction of the current is indicated by the arrows in  FIG. 4 . The current direction of switch S 240  is toward the X side of the panel equivalent capacitor Cp, and the current direction of switch S 290  is toward the Y side of the panel equivalent capacitor Cp. The voltage potential output by voltage source V 21  is greater than that of the voltage sources V 22  and V 23 . Likewise, the voltage potential output by the voltage source V 24  is greater than that of the voltage sources V 25  and V 26 . The voltage potentials output by the voltage sources V 21  and V 24  can be the same or can be different. Similarly, the voltage potentials output by the voltage sources V 22  and V 23  and the voltage sources V 25  and V 26  can be the same or can be different. Inductor L 21  and switch S 24  are electrically connected in series, as are inductor L 22  and switch S 29 .  
         [0042]     Please refer to  FIG. 5 .  FIG. 5  is shows a circuit diagram of a plasma display panel driving circuit  500  according to a second embodiment of the present invention. The driving circuit  500  is a special case of the driving circuit  400  shown in  FIG. 4  in which the voltage sources V 21  and V 24  are the same positive voltage sources, and are labeled as V 3  in  FIG. 5 . In addition, voltage sources V 22 , V 23 , V 25 , and V 26  are all ground. All other components of the driving circuit  500  are the same as the driving circuit  400 , and switches S 211  to S 219 , S 310 , S 241 , and S 291 , inductors L 211  and L 212 , and capacitors C 211  and C 212  correspond to switches S 21  to S 30 , S 240 , and S 290 , inductors L 21  and L 22 , and capacitors C 21  and C 22 , respectively.  
         [0043]     Please refer to  FIG. 6 , which illustrates the operation of the driving circuit  500  of the second embodiment for creating a sustain waveform. Steps contained in the flowchart will be explained as follows.  
         [0044]     Step  600 : Start.  
         [0045]     Step  602 : The switches S 212 , S 213 , S 215 , S 217 , S 218 , and S 310  are turned on. The capacitors C 211  and C 212  are charged to the voltage potential of V 3 . The positive terminal of C 211  is at the node of the connection of S 212  and S 241 . The positive terminal of C 212  is at the node of the connection of S 217  and S 291 . The X side and Y side of the panel equivalent capacitor Cp keep at ground.  
         [0046]     Step  604 : Keep the voltage potential at the X side of the panel equivalent capacitor Cp at ground by turning on the switch S 215 . Charge the Y side of the panel equivalent capacitor Cp by turning on the switches S 217 , S 218 , and S 219 . The voltage potential at Y side of the panel equivalent capacitor Cp goes up to twice the voltage potential of V 3  through the components S 217 , S 218 , S 219 , L 212 , and C 212 .  
         [0047]     Step  606 : Keep the voltage potential at the X side of the panel equivalent capacitor Cp at ground by turning on the switch S 215 . Keep the voltage potential at the Y side of the panel equivalent capacitor Cp at twice the voltage potential of V 3  by turning on the switches S 216  and S 291 .  
         [0048]     Step  608 : Keep the voltage potential at the X side of the panel equivalent capacitor Cp at ground by turning on the switch S 215 . Discharge the Y side of the panel equivalent capacitor Cp by turning on the switches S 217 , S 218 , and S 219 . The voltage potential at Y side of the panel equivalent capacitor Cp goes down to ground through the components S 217 , S 218 , S 219 , L 212 , and C 212 .  
         [0049]     Step  610 : Keep the voltage potential at the X side of the panel equivalent capacitor Cp at ground by turning on the switch S 215 . Keep the voltage potential at the Y side of the panel equivalent capacitor Cp at ground by turning on the switch S 310 . In the meantime, the switches S 212  and S 213  are turned on for charging C 211  to V 3 . The switches S 217  and S 218  are turned on for charging C 212  to V 3 .  
         [0050]     Step  612 : Keep the voltage potential at the Y side of the panel equivalent capacitor Cp at ground by turning on the switch S 310 . Charge the X side of the panel equivalent capacitor Cp by turning on the switches S 212 , S 213 , and S 214 . The voltage potential at X side of the panel equivalent capacitor Cp goes up to twice the voltage potential of V 3  through the components S 212 , S 213 , S 214 , L 211 , and C 211 .  
         [0051]     Step  614 : Keep the voltage potential at the Y side of the panel equivalent capacitor Cp at ground by turning on the switch S 310 . Keep the voltage potential at the X side of the panel equivalent capacitor Cp at twice the voltage potential of V 3  by turning on the switches S 211  and S 241 .  
         [0052]     Step  616 : Keep the voltage potential at the Y side of the panel equivalent capacitor Cp at ground by turning on the switch S 310 . Discharge the X side of the panel equivalent capacitor Cp by turning on the switches S 212 , S 213 , and S 214 . The voltage potential at X side of the panel equivalent capacitor Cp goes down to ground through the components S 212 , S 213 , S 214 , L 211 , and C 211 .  
         [0053]     Step  618 : Keep the voltage potential at the Y side of the panel equivalent capacitor Cp at ground by turning on the switch S 310 . Keep the voltage potential at the X side of the panel equivalent capacitor Cp at ground by turning on the switch S 215 . In the meantime, the switches S 212  and S 213  are turned on for charging C 211  to V 3 . The switches S 217  and S 218  are turned on for charging C 212  to V 3 .  
         [0054]     Step  620 : End.  
         [0055]     It is also allowed to keep the voltage potentials at the X and/or Y sides of the panel equivalent capacitor Cp at twice the voltage potential of V 3  when the other side of the panel equivalent capacitor Cp is charged or discharged. In addition, it is also allowed to charge and discharge the X side of the panel equivalent capacitor Cp during the periods of discharging and charging the Y side of the panel equivalent capacitor Cp, respectively.  
         [0056]     Please refer to  FIG. 7 .  FIG. 7  shows a circuit diagram of a plasma display panel driving circuit  700  according to a third embodiment of the present invention. The driving circuit  700  comprises switches S 31  to S 39 , a capacitor C 31 , inductors L 31  and L 32 , and voltage sources V 31  to V 34 . The driving circuit  700  has an equivalent panel equivalent capacitor Cp of the PDP, which has an X side and a Y side. Switches S 38  and S 39  are unidirectional switches. As indicated by the arrows in  FIG. 7 , the current direction of switch S 38  is toward the X side of panel equivalent capacitor Cp and the current direction of switch S 39  is toward the Y side of panel equivalent capacitor Cp. The voltage potential output by voltage source V 31  is greater than that of the voltage sources V 32 , V 33 , and V 34 . The voltage potentials output by the voltage sources V 32 , V 33 , and V 34  can be the same or can be different. Inductor L 31  and switch S 34  are electrically connected in series, and inductor L 32  and switch S 36  are also electrically connected in series.  
         [0057]     Please refer to  FIG. 8 .  FIG. 8  is shows a circuit diagram of a plasma display panel driving circuit  800  according to a fourth embodiment of the present invention. The driving circuit  800  is a special case of the driving circuit  700  shown in  FIG. 7  in which the voltage sources V 32 , V 33 , and V 34  are all ground. All other components of the driving circuit  800  are the same as the driving circuit  700 , and switches S 311  to S 319 , capacitor C 311 , and inductors L 311  and L 312  correspond to switches S 31  to S 39 , capacitor C 31 , inductors L 31  and L 32 , respectively.  
         [0058]     Please refer to  FIG. 9 , which illustrates the operation of the driving circuit  800  of the fourth embodiment for creating a sustain waveform. Steps contained in the flowchart will be explained as follows.  
         [0059]     Step  900 : Start.  
         [0060]     Step  902 : The switches S 312 , S 313 , S 315 , and S 317  are turned on. The capacitor C 311  is charged to the voltage potential of V 31 . The positive terminal of C 311  is at the node of the connection of S 312 , S 318 , and S 319 . The X side and Y side of the panel equivalent capacitor Cp keep at ground.  
         [0061]     Step  904 : Keep the voltage potential at the X side of the panel equivalent capacitor Cp at ground by turning on the switch S 315 . Charge the Y side of the panel equivalent capacitor Cp by turning on the switches S 312 , S 313 , and S 316 . The voltage potential at Y side of the panel equivalent capacitor Cp goes up to twice the voltage potential of V 31  through the components S 312 , S 313 , S 316 , L 312 , and C 311 .  
         [0062]     Step  906 : Keep the voltage potential at the X side of the panel equivalent capacitor Cp at ground by turning on the switch S 315 . Keep the voltage potential at the Y side of the panel equivalent capacitor Cp at twice the voltage potential of V 31  by turning on the switches S 311  and S 319 .  
         [0063]     Step  908 : Keep the voltage potential at the X side of the panel equivalent capacitor Cp at ground by turning on the switch S 315 . Discharge the Y side of the panel equivalent capacitor Cp by turning on the switches S 312 , S 313 , and S 316 . The voltage potential at Y side of the panel equivalent capacitor Cp goes down to ground through the components S 312 , S 313 , S 316 , L 312 , and C 311 .  
         [0064]     Step  910 : Keep the voltage potential at the X side of the panel equivalent capacitor Cp at ground by turning on the switch S 315 . Keep the voltage potential at the Y side of the panel equivalent capacitor Cp at ground by turning on the switch S 317 . In the meantime, the switches S 312  and S 313  are turned on for charging C 311  to V 31 .  
         [0065]     Step  912 : Keep the voltage potential at the Y side of the panel equivalent capacitor Cp at ground by turning on the switch S 317 . Charge the X side of the panel equivalent capacitor Cp by turning on the switches S 312 , S 313 , and S 314 . The voltage potential at X side of the panel equivalent capacitor Cp goes up to twice the voltage potential of V 31  through the components S 312 , S 313 , S 314 , L 311 , and C 311 .  
         [0066]     Step  914 : Keep the voltage potential at the Y side of the panel equivalent capacitor Cp at ground by turning on the switch S 317 . Keep the voltage potential at the X side of the panel equivalent capacitor Cp at twice the voltage potential of V 31  by turning on the switches S 311  and S 318 .  
         [0067]     Step  916 : Keep the voltage potential at the Y side of the panel equivalent capacitor Cp at ground by turning on the switch S 317 . Discharge the X side of the panel equivalent capacitor Cp by turning on the switches S 312 , S 313 , and S 314 . The voltage potential at X side of the panel equivalent capacitor Cp goes down to ground through the components S 312 , S 313 , S 314 , L 311 , and C 311 .  
         [0068]     Step  918 : Keep the voltage potential at the Y side of the panel equivalent capacitor Cp at ground by turning on the switch S 317 . Keep the voltage potential at the X side of the panel equivalent capacitor Cp at ground by turning on the switch S 315 . In the meantime, the switches S 312  and S 313  are turned on for charging C 311  to V 31 .  
         [0069]     Step  920 : End.  
         [0070]     Please refer to  FIG. 10 .  FIG. 10  shows a circuit diagram of a plasma display panel driving circuit  1000  according to a fifth embodiment of the present invention. The driving circuit  1000  combines the two inductors L 311  and L 312  shown in  FIG. 8  into one and combines the two switches S 318  and S 319  into one. The driving circuit  1000  comprises switches S 321  to S 328 , a capacitor C 321 , and an inductor L 321 . The driving circuit  1000  has an equivalent panel equivalent capacitor Cp of the PDP, which has an X side and a Y side. Switch S 328  is a unidirectional switch, and as indicated by the arrows in  FIG. 10 , the current direction of switch S 328  is toward the node formed by the connection of switches S 324  and S 326 .  
         [0071]     Please refer to  FIG. 11 , which illustrates the operation of the driving circuit  1000  of the fifth embodiment for creating a sustain waveform. Steps contained in the flowchart will be explained as follows.  
         [0072]     Step  1100 : Start.  
         [0073]     Step  1102 : The switches S 322 , S 323 , S 325 , and S 327  are turned on. The capacitor C 321  is charged to the voltage potential of V 31 . The positive terminal of C 321  is at the node of the connection of S 322  and S 328 . The X side and Y side of the panel equivalent capacitor Cp keep at ground.  
         [0074]     Step  1104 : Keep the voltage potential at the X side of the panel equivalent capacitor Cp at ground by turning on the switch S 325 . Charge the Y side of the panel equivalent capacitor Cp by turning on the switches S 322 , S 323 , and S 326 . The voltage potential at Y side of the panel equivalent capacitor Cp goes up to twice the voltage potential of V 31  through the components S 322 , S 323 , S 326 , L 321 , and C 321 .  
         [0075]     Step  1106 : Keep the voltage potential at the X side of the panel equivalent capacitor Cp at ground by turning on the switch S 325 . Keep the voltage potential at the Y side of the panel equivalent capacitor Cp at twice the voltage potential of V 31  by turning on the switches S 321 , S 328 , and S 326 .  
         [0076]     Step  1108 : Keep the voltage potential at the X side of the panel equivalent capacitor Cp at ground by turning on the switch S 325 . Discharge the Y side of the panel equivalent capacitor Cp by turning on the switches S 322 , S 323 , and S 326 . The voltage potential at Y side of the panel equivalent capacitor Cp goes down to ground through the components S 322 , S 323 , S 326 , L 321 , and C 321 .  
         [0077]     Step  1110 : Keep the voltage potential at the X side of the panel equivalent capacitor Cp at ground by turning on the switch S 325 . Keep the voltage potential at the Y side of the panel equivalent capacitor Cp at ground by turning on the switch S 327 . In the meantime, the switches S 322  and S 323  are turned on for charging C 321  to V 31 .  
         [0078]     Step  1112 : Keep the voltage potential at the Y side of the panel equivalent capacitor Cp at ground by turning on the switch S 327 . Charge the X side of the panel equivalent capacitor Cp by turning on the switches S 322 , S 323 , and S 324 . The voltage potential at X side of the panel equivalent capacitor Cp goes up to twice the voltage potential of V 31  through the components S 322 , S 323 , S 324 , L 321 , and C 321 .  
         [0079]     Step  1114 : Keep the voltage potential at the Y side of the panel equivalent capacitor Cp at ground by turning on the switch S 327 . Keep the voltage potential at the X side of the panel equivalent capacitor Cp at twice the voltage potential of V 31  by turning on the switches S 321 , S 328 , and S 324 .  
         [0080]     Step  1116 : Keep the voltage potential at the Y side of the panel equivalent capacitor Cp at ground by turning on the switch S 327 . Discharge the X side of the panel equivalent capacitor Cp by turning on the switches S 322 , S 323 , and S 324 . The voltage potential at X side of the panel equivalent capacitor Cp goes down to ground through the components S 322 , S 323 , S 324 , L 321 , and C 321 .  
         [0081]     Step  1118 : Keep the voltage potential at the Y side of the panel equivalent capacitor Cp at ground by turning on the switch S 327 . Keep the voltage potential at the X side of the panel equivalent capacitor Cp at ground by turning on the switch S 325 . In the meantime, the switches S 322  and S 323  are turned on for charging C 321  to V 31 .  
         [0082]     Step  1120 : End.  
         [0083]     Please refer to  FIG. 12 .  FIG. 12  is shows a circuit diagram of a plasma display panel driving circuit  1200  according to a sixth embodiment of the present invention. The driving circuit  1200  comprises switches S 331  to S 338 , capacitor C 331 , and inductor L 331 , which correspond to switches S 321  to S 328 , capacitor C 321 , and inductor L 321 , of the driving circuit  1000  respectively. Driving circuit  1200  further includes a Diode D 332 . In the driving circuit  1200 , switches S 321  to S 328  are n-channel MOSFETs, although p-channel MOSFETs and other transistor types such as insulated gate bipolar transistors (IGBT) could also be used as well. Diode D 331  and switch S 338  together form the unidirectional switch S 328  shown in  FIG. 10 .  
         [0084]     In summary, the present invention driving circuits utilize switches to make the sustained voltage twice the voltage potential supplied by the voltage source. The voltage stress of some components will therefore be lower. In addition, the numbers of components can be reduced in the driving circuit.  
         [0085]     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.