PURPOSE: To stop oscillation caused by first and second switching means when a discharge lamp comes off and automatically release stop of oscillation when the discharge lamp is fit and lit after stop of oscillation, with simple circuit constitution.
CONSTITUTION: A lamp detecting circuit 33 detects whether a discharge lamp 31 is fixed to an output circuit 30 or not, and when the lamp detecting circuit 33 detects that the discharge lamp 13 is not fixed, an oscillation stop circuit 24 stops oscillation caused by turning on and off of first and second switching means 21, 22. In the state that the discharge lamp 31 comes off, oscillation of the switching means 21, 22 is stopped, and when the discharge lamp 31 is fixed from the coming off state, stop of oscillation of the switching means 21, 22 is released.
KAKIYA TSUTOMU
TAKAHASHI YUJI
