LARGE-SIZED VIDEO DISPLAY DEVICE

摘要

PURPOSE:To eliminate the need for large power source capacity and to prevent a flicker in low-gradation mode by providing an oscillator which supplies a specific clock signal at every lamp unit or at every plural lamp units and operating the oscillators asynchronously. CONSTITUTION:When video data is inputted, a pulse width converting circuit 8 outputs a pulse with pulse width corresponding to the excitation period of each light emitting element 4 to an excitation control circuit 10 at specific timing synchronized with the clock supplied from the oscillator 12. Then an AC power source 6 operates in synchronism with the clock supplied from the oscillator 12 so that an integer multiple of the period of the AC output is coincident with the excitation period of one gradation, thereby starting the excitation of respective light emitting elements 4 in the same phase at all times. The respective oscillators 12 are shifted in phase at random among AC power sources 6 synchronized with the oscillators 12 to disperse the influence of the load variation of each AC power source 6. Consequently, the flicker in low- gradation mode is prevented and the power source capacity is reduced.