DISCHARGE LAMP LIGHTING DEVICE

摘要

PROBLEM TO BE SOLVED: To prevent an unstable phenomenon such as deformation of a discharge arc in a discharge lamp lighting device reducing the curve of the discharge arc caused by the harmful gravitational force-induced convection occurring when a discharge lamp, particularly a high-intensity discharge lamp (HID lamp), is horizontally lighted. SOLUTION: This discharge lamp lighting device is provided with a generating means 13 generating the wave-form signal so that the center line of the wave-form having the frequency component of the acoustic resonance frequency exciting the mode straightening a discharge arc is kept at a constant level and a modulating means 14 modulating the wave-form signal so that the center line of the wave-form signal is changed in reverse polarities in turn at the modulation frequency lower than the acoustic resonance frequency and generating the modulation signal. There is a period when the modulation depthα/βbecomes a value or below at the time of rated lighting in the lighting initial stage of a discharge lamp, whereαis the peak-to-peak value of the wave-form signal, andβis the root-mean-square value of the modulation signal.