Abstract:
A driving circuit for the sustain waveforms of plasma display panel (PDP) includes voltage clamping and energy recovery. The PDP functions as an equivalent capacitor having X and Y sides. A Scan IC has a transistor QH coupled between a first terminal of the Scan IC and the Y side and a transistor QL coupled between a second terminal of the Scan IC and the Y side. The first terminal of the Scan IC is coupled with a first voltage source. A first switch is coupled to coupled to the second terminal of the Scan IC, a second switch is coupled between a second voltage source and the X side, and a third switch is coupled with both the X side and a fourth switch. The fourth switch is also coupled to the second terminal of the Scan IC and serially to an inductor, a fifth switch, and ground.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application claims the benefit of priority from U.S. Provisional Patent Application No. 60/595,308, filed on Jun. 22, 2005, which is hereby incorporated by reference as if set forth in full in this document for all purposes. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a driving circuit, and more particular, to a driving circuit for plasma display panel (PDP).  
         [0004]     2. Description of the Prior Art  
         [0005]      FIG. 1  is a prior art driving circuit  100  of a plasma display panel. An equivalent capacitor of the PDP is marked as Cpanel. There are switches S 1 , S 3 , and an energy recovery circuit  110  coupled to the X-side of panel. S 1  is coupled to a voltage source V 1  and S 3  is coupled to ground. The energy recover circuit  110  comprises a switch S 5  and a diode D 5  in series coupled in parallel with serially coupled switch S 6  and a diode D 6 . The two parallel circuits are coupled between an inductor L 1  (L 1  couples with the X-side of the panel) and a capacitor C 1  for energy recovery, which is also coupled to ground.  
         [0006]     Similarly, coupled to the Y-side of the panel are switches S 2 , S 4 , and an energy recovery circuit  1   20 . S 5 , S 6 , S 7  and S 8  are switches. S 2  is coupled to a voltage source V 2  and S 4  is coupled to ground. The energy recover circuit  120  comprises a switch S 7  and a diode D 7  in series coupled in parallel with serially coupled switch S 8  and a diode D 8 . The two parallel circuits are coupled between an inductor L 2  (L 2  couples with the Y-side of the panel) and a capacitor C 2  for energy recovery, which is also coupled to ground.  
         [0007]     The X-side circuit and the Y-side circuit together form the capacitor Cpanel. Details of exact functioning of the driving circuit  100  are well known in the art and will be omitted here for brevity. However, it is important to notice that the driving circuit  100  requires quite a few components, making it expensive to make. Cost conscious consumers desiring a PDP demand lower prices and thus make PDPs comprising similar circuits uncompetitive in today&#39;s market.  
       SUMMARY OF THE INVENTION  
       [0008]     It is therefore an objective of the claimed invention to provide a driving circuit for a PDP having fewer components, at a reduced cost.  
         [0009]     A driving circuit for a plasma display panel according to the claimed invention includes a plasma display panel acting as an equivalent capacitor having X and Y sides. A Scan IC has a transistor QH coupled between a first terminal of the Scan IC and the Y side and a transistor QL coupled between a second terminal of the Scan IC and the Y side. The first terminal of the Scan IC is coupled with a first voltage source. A first switch is coupled to the second terminal of the Scan IC, a second switch is coupled between a second voltage source and the X side, and a third switch is coupled with both the X side and a fourth switch. The fourth switch is also coupled to the second terminal of the Scan IC and serially to an inductor, a fifth switch, and ground.  
         [0010]     Another driving circuit for a plasma display panel according to the claimed invention includes a plasma display panel acting as an equivalent capacitor having X and Y sides, with the X side coupled directly to ground. A Scan IC has a transistor QH coupled between a first terminal of the Scan IC and the Y side and a transistor QL coupled between a second terminal of the Scan IC and the Y side. The first terminal of the Scan IC is coupled with a first voltage source. A first switch is coupled between a second voltage source and the second terminal of the Scan IC and a second switch is coupled to ground and serially coupled with an inductor and the second terminal of the Scan IC.  
         [0011]     The advantage of the claimed invention is that the necessary driving waveforms can be generated using the claimed circuit at a reduced cost.  
         [0012]     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  
       [0013]      FIG. 1  is a driving circuit for a PDP according to prior art.  
         [0014]      FIG. 2  is a driving circuit for a PDP according to the present invention.  
         [0015]      FIG. 3  is one embodiment of the driving circuit of  FIG. 2 .  
         [0016]      FIG. 4  is another embodiment of the driving circuit of  FIG. 2 .  
         [0017]      FIG. 5  is one embodiment of the driving circuit of  FIG. 4 .  
         [0018]      FIG. 6  is another embodiment of the driving circuit of  FIG. 4 .  
         [0019]      FIG. 7  is another driving circuit for a PDP according to the present invention.  
         [0020]      FIG. 8  is one embodiment of the driving circuit of  FIG. 7 .  
         [0021]      FIG. 9  is another embodiment of the driving circuit of  FIG. 7 .  
         [0022]      FIG. 10  is one embodiment of the driving circuit of  FIG. 9 .  
         [0023]      FIG. 11  is another embodiment of the driving circuit of  FIG. 9 .  
         [0024]      FIG. 12  is another driving circuit for a PDP according to the present invention.  
         [0025]      FIG. 13  is one embodiment of the driving circuit of  FIG. 12 .  
         [0026]      FIG. 14  is an embodiment of the driving circuit of  FIG. 13 .  
         [0027]      FIG. 15  is a flow chart of creating a sustain waveform in the driving circuit of  FIG. 6 .  
         [0028]      FIG. 16  is a flow chart of creating a sustain waveform in the driving circuit of  FIG. 11 .  
         [0029]      FIG. 17  is a flow chart of creating a sustain waveform in the driving circuit of  FIG. 14 . 
     
    
     DETAILED DESCRIPTION  
       [0030]     Please refer to  FIG. 2  that is a driving circuit  200  for a PDP according to the present invention that comprises switches S 22 , S 23 , S 24 , S 25 , and S 26 , a Scan IC  99 , an inductor L 21 , a capacitor C 21 , and a capacitor Cp having X and Y sides that is the equivalent capacitor formed by the PDP.  
         [0031]     A first voltage source V 21  is coupled with a first terminal of the Scan IC  99 . The switch S 23  is coupled between ground and a second terminal of the Scan IC  99 . The Scan IC  99  comprises a transistor QH coupled between the first terminal of the Scan IC and the Y side and a transistor QL coupled between the second terminal of the Scan IC and the Y side. The switch S 22  is coupled between a second voltage source V 22  and the X side. The switch S 24  is coupled between ground and both the X side and the switch S 26 . The switch S 26  is also coupled to the second terminal of the Scan IC  99  and to one end of the inductor L 21 . The other end of the inductor L 21  couples with the switch S 25 , the capacitor C 21 , and ground in series. Voltage sources V 21  and V 22  can be the same or different.  
         [0032]      FIG. 3  is another driving circuit  300  that is one embodiment of the driving circuit  200  of  FIG. 2 . Connections and functionalities of all like numbered elements are the same as in  FIG. 2 , except that the inductor L 21  of  FIG. 2  has been replaced with inductors L 24  and L 25 . As is illustrated in  FIG. 3 , the inductor L 25  is coupled between the switch S 26  and the switch S 25 , and the inductor L 24  is coupled between the switch S 25  and the second terminal of the Scan IC  99 . The slopes of rising and falling of sustain waveforms can be adjusted by these inductors.  
         [0033]      FIG. 4  is another driving circuit  400  that is a modified version of the PDP driving circuit  200  in  FIG. 2 . Connections and functionalities of all like numbered elements are the same as in  FIG. 2 . The difference between the driving circuit  200  and the driving circuit  400  is that the driving circuit  400  further includes a switch S 21  coupled between the first voltage source V 21  and the first terminal of the Scan IC  99 .  
         [0034]     Please refer now to  FIG. 5  that illustrates a driving circuit  500 , which is a variation of the circuit  400  shown in  FIG. 4 . In  FIG. 5 , connections and functionalities of all like numbered elements are the same as in  FIG. 4 , except that the inductor L 21  of  FIG. 4  has been replaced with inductors L 22  and L 23 . As is illustrated in  FIG. 5 , the inductor L 23  is coupled between the switch S 26  and the switch S 25 , and the inductor L 22  is coupled between the switch S 25  and the second terminal of the Scan IC  99 .  
         [0035]      FIG. 6  is another driving circuit  600  that is a modified version of the PDP driving circuit  400  in  FIG. 4  with the connections and functionalities of all like numbered elements the same as in  FIG. 4 . The difference between the driving circuit  400  and the driving circuit  600  is that the driving circuit  600  replaces all of the switches S 21 , S 22 , S 23 , S 24 , S 25 , and S 26  with n-channel MOSFETs that are labeled S 211 , S 212 , S 213 , S 214 , S 21   5 , and S 216  respectively. Here, the voltage sources V 21  and V 22  in the driving circuit  400  have the same voltage potential and are marked as V 20  to indicate the situation. According to the  FIG. 6 , the operation for the sustain waveform is as following steps and according to the flow chart in  FIG. 15 . During all steps, switches not indicated as being turning on are assumed to be turned off by default. Obviously, the following steps can be repeated as desired.  
         [0036]     Step  210 : Start.  
         [0037]     Step  211 : Keep the voltage potential at the X side of the capacitor Cp at V 20  by turning on the switch S 212 . Keep the Y side of the capacitor Cp at ground by turning on the switches S 213  and QL of the Scan IC.  
         [0038]     Step  212 : Keep the voltage potential at the X side of the capacitor Cp at V 20  by turning on the switch S 212 . Charge the Y side of the capacitor Cp by turning on the switches S 215  and QL of the Scan IC. The voltage potential at Y side of the capacitor Cp goes up to V 20  through the components S 215 , QL of the Scan IC, L 21  and C 21 .  
         [0039]     Step  213 : Keep the voltage potential at the X side of the capacitor Cp at V 20  by turning on the switch S 212 . Keep the voltage potential at the Y side of the capacitor Cp at V 20  by turning on the switches S 211  and QH of the Scan IC;  
         [0040]     Step  214 : Keep the voltage potential at the Y side of the capacitor Cp at V 20  by turning on the switch S 211  and QH of the Scan IC. Discharge the X side of the capacitor Cp by turning on the switches S 215  and S 216 . The voltage potential at X side of the capacitor Cp goes down to ground through the components S 215 , S 216 , L 21  and C 21 .  
         [0041]     Step  215 : Keep the voltage potential at the Y side of the capacitor Cp at V 20  by turning on the switch S 211  and QH of the Scan IC. Keep the voltage potential at the X side of the capacitor Cp at ground by turning on the switch S 214 .  
         [0042]     Step  216 : Keep the voltage potential at the Y side of the capacitor Cp at V 20  by turning on the switch S 211  and QH of the Scan IC. Charge the X side of the capacitor Cp by turning on the switches S 215  and S 216 . The voltage potential at X side of the capacitor Cp goes up to V 20  through the components S 215 , S 216 , L 21  and C 21 .  
         [0043]     Step  217 : Keep the voltage potential at the Y side of the capacitor Cp at V 20  by turning on the switch S 211  and QH of the Scan IC. Keep the voltage potential at the X side of the capacitor Cp at V 20  by turning on the switch S 212 .  
         [0044]     Step  218 : Keep the voltage potential at the X side of the capacitor Cp at V 20  by turning on the switch S 212 . Discharge the Y side of the capacitor Cp by turning on the switches S 215  and QL of the Scan IC. The voltage potential at Y side of the capacitor Cp goes down to ground through the components S 215 , QL of the Scan IC, L 21  and C 21 .  
         [0045]     Step  220 : End.  
         [0046]      FIG. 7  is a second major embodiment of a driving circuit  700  for a PDP according to the present invention that comprises switches S 32 , S 33 , S 34 , S 35 , and S 36 , a Scan IC  99 , an inductor L 31 , and a capacitor Cp having X and Y sides that is the equivalent capacitor formed by the PDP.  
         [0047]     A first voltage source V 31  is coupled to a first terminal of the Scan IC  99 . The switch S 32  is coupled between a second voltage source V 32  and the X side. The switch S 33  is coupled between a second terminal of the Scan IC  99  and a third voltage source V 33 . The switch S 34  is coupled between a fourth voltage source V 34  and both the X side and the switch S 36 . The switch S 36  is also coupled to the second terminal of the scan IC  99  and to one end of the inductor L 31 . The other end of the inductor L 31  couples with the switch S 35  and ground in series. The Scan IC  99  comprises a transistor QH coupled between the first terminal of the Scan IC  99  and the Y side and a transistor QL coupled between the second terminal of the Scan IC  99  and the Y side. Voltage sources V 31  and V 32  are positive voltage sources and V 33  and V 34  are negative voltage sources. V 31  and V 32  can be the same or different. V 33  and V 34  can be the same or different.  
         [0048]     The major differences between the driving circuit  200  shown in  FIG. 2  and the driving circuit  700  shown in  FIG. 7  are that the capacitor C 21  in  FIG. 2  has been removed and the switches S 33  and S 34  (S 23  and S 24  in  FIG. 2 ) are now connected to voltage sources V 33  and V 34  instead of ground.  
         [0049]      FIG. 8  is a driving circuit  800  that is one embodiment of the driving circuit  700  of  FIG. 7 . Connections and functionalities of all like numbered elements are the same as in  FIG. 7 , except that the inductor L 31  of  FIG. 7  has been replaced with inductors L 34  and L 35 . As is illustrated in  FIG. 8 , the inductor L 35  is coupled between the switch S 36  and the switch S 35 , and the inductor L 34  is coupled between the switch S 25  and the second terminal of the Scan IC  99 .  
         [0050]      FIG. 9  is a driving circuit  850  that is a modified version of the PDP driving circuit  700  in  FIG. 7 . Connections and functionalities of all like numbered elements are the same as in  FIG. 7 , The difference between the driving circuit  700  and the driving circuit  850  is that the driving circuit  850  further comprises a switch S 31  coupled between the first voltage source V 31  and the first terminal of the Scan IC  99 .  
         [0051]     Please refer now to the driving circuit  900  shown in  FIG. 10 , which is an additional variation of the driving circuit  850  shown in  FIG. 9 . In  FIG. 10 , connections and functionalities of all like numbered elements are the same as in  FIG. 9 , except that the inductor L 31  of  FIG. 9  has been replaced with inductors L 32  and L 33 . The inductor L 33  is coupled between the switch S 36  and the switch S 35  and the inductor L 32  is coupled between the switch S 35  and the second terminal of the Scan IC  99 .  
         [0052]      FIG. 11  is a driving circuit  950  that is another modified version of the PDP driving circuit  850  in  FIG. 9 . Connections and functionalities of all like numbered elements are the same as in  FIG. 9 , The difference between the driving circuit  850  and the driving circuit  950  is that the driving circuit  950  replaces all of the switches S 31 , S 32 , S 33 , S 34 , S 35 , and S 36  with n-channel MOSFETs that are labeled S 311 , S 312 , S 313 , S 314 , S 315 , and S 316  respectively. The voltage sources V 31  and V 32  have the same voltage potential and are marked as V 300 . The voltage sources V 33  and V 34  have the same voltage potential and are marked as V 310 .  
         [0053]     The operation for the sustain waveform is as in the following steps and as shown in  FIG. 16 . During all steps, switches not indicated as being turning on are assumed to be turned off by default. Obviously, the following steps can be repeated as desired.  FIG. 9  would obviously operate similarly with  FIG. 11  assuming the appropriate substitution of element number labels.  
         [0054]     Step  310 : Start.  
         [0055]     Step  311 : Keep the voltage potential at the X side of the capacitor Cp at V 300  by turning on the switch S 312 . Keep the Y side of the capacitor Cp at V 310  by turning on the switches S 313  and QL of the Scan IC.  
         [0056]     Step  312 : Keep the voltage potential at the X side of the capacitor Cp at V 300  by turning on the switch S 312 . Charge the Y side of the capacitor Cp by turning on the switches S 315  and QL of the Scan IC. The voltage potential at Y side of the capacitor Cp goes up to V 300  through the components S 315 , QL of the Scan IC and L 31 .  
         [0057]     Step  313 : Keep the voltage potential at the X side of the capacitor Cp at V 300  by turning on the switch S 312 . Keep the voltage potential at the Y side of the capacitor Cp at V 300  by turning on the switches S 311  and QH of the Scan IC.  
         [0058]     Step  314 : Keep the voltage potential at the Y side of the capacitor Cp at V 300  by turning on the switch S 311  and QH of the Scan IC. Discharge the X side of the capacitor Cp by turning on the switches S 315  and S 316 . The voltage potential at X side of the capacitor Cp goes down to V 310  through the components S 315 , S 316  and L 31 .  
         [0059]     Step  315 : Keep the voltage potential at the Y side of the capacitor Cp at V 300  by turning on the switch S 311  and QH of the Scan IC. Keep the voltage potential at the X side of the capacitor Cp at V 310  by turning on the switch S 314 .  
         [0060]     Step  316 : Keep the voltage potential at the Y side of the capacitor Cp at V 300  by turning on the switch S 311  and QH of the Scan IC. Charge the X side of the capacitor Cp by turning on the switches S 315  and S 316 . The voltage potential at X side of the capacitor Cp goes up to V 300  through the components S 315 , S 316  and L 31 .  
         [0061]     Step  317 : Keep the voltage potential at the Y side of the capacitor Cp at V 300  by turning on the switch S 311  and QH of the Scan IC. Keep the voltage potential at the X side of the capacitor Cp at V 300  by turning on the switch S 312 .  
         [0062]     Step  318 : Keep the voltage potential at the X side of the capacitor Cp at V 300  by turning on the switch S 312 . Discharge the Y side of the capacitor Cp by turning on the switches S 315  and QL of the Scan IC. The voltage potential at Y side of the capacitor Cp goes down to V 310  through the components S 315 , QL of the Scan IC and L 31 .  
         [0063]     Step  320 : End.  
         [0064]      FIG. 12  is another major embodiment of a driving circuit  970  for a PDP according to the present invention that comprises switches S 43  and S 45 , a Scan IC  99 , an inductor L 41 , and a capacitor Cp that is the equivalent capacitor formed by the PDP and having X and Y sides .  
         [0065]     On the Y side of the equivalent capacitor Cp, a first voltage source V 41  is coupled to a first terminal of the Scan IC  99 . The Scan IC  99  comprises a transistor QH coupled between the first terminal of the Scan IC  99  and the Y side and a transistor QL coupled between a second terminal of the Scan IC  99  and the Y side. The switch S 43  is coupled between a second voltage source V 43  and the second terminal of the Scan IC  99 . The second terminal of the Scan IC  99  also couples with the inductor L 41 , the switch S 45 , and ground in series. The voltage source V 41  is a positive voltage source and V 43  is a negative voltage source. The X side of the capacitor Cp couples to directly ground.  
         [0066]      FIG. 13  illustrates another PDP driving circuit  980  according to the present invention. All connection and functionalities of like numbered elements in the driving circuit  980  of  FIG. 13  are the same as in the driving circuit  970  of  FIG. 12 . The difference between the driving circuit  980  and the driving circuit  970  is that the driving circuit  980  further comprises a switch S 41  coupled between the first voltage source V 41  and the first terminal of the Scan IC  99 .  
         [0067]      FIG. 14  is a driving circuit  990  that is one embodiment of the driving circuit  980  of  FIG. 13  where the switches S 41 , S 43 , and S 45  in  FIG. 13  have been replaced by n-channel MOSFETs S 411 , S 413 , and S 415  respectively. All other connections and components remain the same. The X side of the capacitor Cp is always coupled to ground. According to the  FIG. 14 , the operation for a sustain waveform is as shown in the following steps and in  FIG. 17 . Obviously, the driving circuit  980  of  FIG. 13  would function similarly. During all steps, switches not indicated as being turning on are assumed to be turned off by default. The following steps can be repeated as desired.  
         [0068]     Step  410 : Start.  
         [0069]     Step  411 : Keep the voltage potential at Y side of the capacitor Cp at V 43  by turning on the switches S 413  and QL of the Scan IC.  
         [0070]     Step  412 : Charge the Y side of the capacitor Cp by turning on the switches S 415  and QL of the Scan IC. The voltage potential at Y side of the capacitor Cp goes up to V 41  through the components S 415 , QL of the Scan IC and L 41 .  
         [0071]     Step  413 : Keep the voltage potential at the Y side of the capacitor Cp at V 41  by turning on the switches S 411  and QH of the Scan IC.  
         [0072]     Step  414 : Discharge the Y side of the capacitor Cp by turning on the switches S 415  and QL of the Scan IC. The voltage potential at Y side of the capacitor Cp goes down to V 43  through the components S 415 , QL of the Scan IC, and L 41 .  
         [0073]     Step  416 : End.  
         [0074]     The present invention provides a new driving circuit for a PDP that can generate the necessary driving waveforms at a reduced cost by utilizing fewer components than current related art.  
         [0075]     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.