METHOD FOR DRIVING FLUORESCENT DISPLAY TUBE FILAMENT

PURPOSE:To prevent the generation of a flicker of a display even if a lighting duty in static lighting is small by specifying the frequency of an AC voltage applied to a cathode filament, and a repeating frequency for a display given to a grid and/or an anode. CONSTITUTION:A relation between the frequency f2 of an AC voltage applied to a cathode filament and the repeating frequency f1 of a voltage applied to a grid terminal and/or an anode terminal is set to f2=(n+1/m).f1, and also, f1/m is set to a frequency or above which does not flicker. In this regard, (n) and (m) are natural numbers. As a result, within the time of m/f1, the voltage between the anode and the grid, and the cathode filament is averaged, and a flicker can be prevented by setting f1/m to a frequency by which a flicker is inconspicuous. In such a way, even when the lighting duty ratio of a static lighting fluorescent tube is small, the flicker of a display is prevented.