such an amount as to enable the next sustain discharge are stored on the surface of the MgO protective film on the common electrode X and the scanning electrode Y of the selected cell.
Thereafter, in the sustain discharge period, the voltage of the common electrodes X gradually rises by the operation of the power recovering circuit which will be described later. Subsequently, in the vicinity of the peak of the rise, the voltage of the common electrodes X is clamped to (Vs/2).
Next, the voltage of the scanning electrodes Y gradually drops. At this time, the power recovering circuit recovers part of the charges. The operation of the power recovering circuit will be described later. In the vicinity of the peak of the drop, the voltage of the scanningSW7 are turned OFF. At this time, the voltage of the first signal line OUTA (first potential) becomes (+Vs/2), and the voltage of the second signal line OUTB (second potential) and the voltage of the output line OUTC become the ground level (t1).
Next, by turning ON the switch SW6 in the power recovering circuit 21, L-C resonance occurs with the coil L1 and the capacitance of the load 20, and the charges recovered in the capacitor C2 is supplied to the load 20 via the switch SW6 and the coil L1 (t2). By such a flow of the current, the voltage of the output line OUTC which is applied to the common electrode X gradually rises as shown in the times t2 to t3 in FIG. 18. The