DISCHARGE LAMP LIGHTING CIRCUIT

摘要

A discharge lamp lighting circuit is provided to suppress an influence of a variation of an interelectrode voltage and to control supplied power. A discharge lamp lighting circuit is used for supplying electric power to a discharge lamp. A control unit generates a control signal for controlling the amount of electric power on the basis of an interelectrode voltage of the discharge lamp. An electric power unit supplies the electric power to the discharge lamp on the basis the control signal of the control unit. The control unit includes a differential calculation part(15) for differentiating a signal according to an interelectrode voltage with respect to time in order to generate a first differential signal, and a first integral calculation part(16) for integrating a second differential signal which monotonously increases and decreases as the first differential signal increases and decreases with respect to time in order to generate a first integral signal. The control unit generates a control signal in order to reduce the electric power according to an increase of the first integral signal.