PURPOSE: To reduce the brightness level of a display element in its micro-trickle electric discharge condition by impressing high voltage continuously upon the display element until the micro-trickle electric discharge condition is attained after the initiation of high-voltage impression, and impressing the high voltage intermittently upon the display element in such a degree that remaining ions are not annihilated after the display element may be ready for transference to the micro-trickle electric discharge condition.
CONSTITUTION: A switching control circuit 21 turns continuously on a high-voltage switching element S2 during a constant period required until a display element 10 attains its micro-trickle electric discharge condition after the high-voltage switching element S2 is turned on before a point of time when a main electric discharge current is impressed upon the display element 10. After the lapse of the constant period, the control circuit controls the high-voltage switching element S2 in such a manner that the switching element may repeat the on-off action within an off period shorter than the annihilation time of ions remaining in the display element 10. Namely, high voltage is impressed continuously upon the display element 10 until the display element attains the micro-trickle electric discharge condition after the initiation of high-voltage impression, and impressed intermittently upon the display element in such a degree that remaining ions are not annihilated after the display element may be ready for transference to the micro-trickle electric discharge condition. This can reduce the brightness level of the display element 10 in the micro-trickle electric discharge condition.
SAKAGUCHI YOSHIYASU
SHIOHAMA EIJI
MATSUSHIMA HIROSHI
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