Discharge lamp lighting circuit

A discharge lamp lighting circuit comprising:

• a DC—DC converting circuit for receiving a DC input voltage and converting the DC input voltage into a desired DC voltage;
• a DC-AC converting circuit for converting an output voltage of the DC—DC converting circuit into an AC voltage and then supplying the AC voltage to a discharge lamp;
• a starting circuit for generating a starting pulse to be sent to the discharge lamp;
• and
• a control circuit for controlling a power to be applied to the discharge lamp,
• wherein the control circuit carries out power control in a steady state of the discharge lamp in response to a detection signal for a voltage applied to the discharge lamp and a current flowing to the discharge lamp and carries out output control of the DC—DC converting circuit for controlling a power to be transiently applied to the discharge lamp before a transition to the power control;
• the power to be transiently applied is set to be higher than the power in the steady state and light emission of the discharge lamp is promoted to cause a luminous flux of the discharge lamp to approximate to a luminous flux in a steady state in a short time;
• and
• an increment in the power to be transiently applied in the above which exceeds the power in the steady state is specified by the control circuit corresponding to a voltage applied to the discharge lamp, a variation in the voltage and a time elapsed from a time that the discharge lamp is lighted up or a start of an operation of a lighting circuit.