OPTICAL EMISSION ELECTRONIC TUBE LIGHTING DEVICE

摘要

PURPOSE:To eliminate flickering or lighting off when a dim level is changed by setting a time-based change ratio of a lamp current close to the maximum value of a lamp voltage when a predetermined voltage is applied to a filament for dimming to be smaller than that except the lamp voltage maximum value. CONSTITUTION:After a predtermined voltage is applied to both ends of a filament (f) of a optical emission electronic tube G from an AC power supply Vs through a filament heting circuit 2, power for obtaining a desired light output is supplied from a lamp power supply circuit 1 to the electronic tube G in accordance with a dim signal. A time-based change ratio of a lamp current close to a lamp current at which a lamp voltage becomes the macimum value is set to be smaller than the time-based change ratio of the lamp current at other than the lamp current with the maximum lamp voltage by an output change setting circuit 9 at this time.