The temporal effects of charged and metastable particles in the micro-discharges of an ac plasma display panel (ac-PDP) were investigated under actual driving conditions. The discharge gas used in the 4-in PDP was Neon + 4% Xenon. The discharge characteristics in terms of the time scale related to the space-charge decay, wall charge decay, metastable decay, and charge accumulation were investigated using a pulse technique. ForNeon+4% Xenon gas-mixture discharges of 500 torr, 4 mus was related to the time scale of the space-charge decay and wall-charge accumulation time. The minimum sustain voltage started to dramatically increase at 20 mus, which was related to the time scale of the metastable particles. Whereas, after 40 mus, the minimum sustain voltage slowly increased with a slope of 0.01581, which was related to the inverse of the time scale of the wall charge decay.