LIGHTING DEVICE OF DISCHARGE LAMP

摘要

PROBLEM TO BE SOLVED: To prevent a misjudgment by the life judging circuit of the end of life of a discharge lamp when tube voltage rises when the discharge lamp is dimmer controlled. SOLUTION: A lighting device of a discharge lamp which has a dimmer function of the discharge lamp comprises a tube voltage detecting circuit 15 which enables to change the detecting tube voltage Vd against the tube voltage Vpp of the discharge lamp at dimmer control, in order to restrain the change of the detecting tube voltage Vd against the tube voltage Vpp of the discharge lamp 3 when dimmer controlled.