Patent ID: 8009122

Claim:
A plasma display device comprising: a plasma display panel provided with at least a plurality of discharge cells each having at least discharge gas, a pair of sustain electrodes which generate sustain discharge for light-emission display, and a phosphor which generates visible light by being excited by ultraviolet rays generated by said sustain discharge; and a driving circuit which applies a sustain pulse voltage between said pair of sustain electrodes for generating said sustain discharge; wherein said sustain pulse voltage is comprised of a first portion having a main portion of a first voltage Vp V and a second portion succeeding said first portion in time and having a main portion of a second voltage Vs V higher than said first voltage Vp V, said sustain discharge is comprised of a pre-discharge and a main discharge succeeding said pre-discharge in time, and said first voltage Vp V is selected to satisfy the following inequality: Vpmin≦Vp<Vs, where Vpmin V is a minimum of said first voltage Vp V which stabilizes said sustain discharge; and wherein a load factor is defined as a ratio of a number of lighted cells among said plurality of discharge cells at a given point of time to a total number of said plurality of discharge cells, a pre-discharge ratio is defined as a ratio of an integral of a waveform of a discharge current integrated over a time of said pre-discharge to an integral of a waveform of a discharge current generated by one sustain pulse voltage in said sustain discharge, and when said load factor of a display is smaller, said first voltage Vp V and said second voltage Vs V are selected to make said pre-discharge ratio greater than that when said load factor of a display is larger.