Patent ID: 7368881

Claim:
A discharge lamp lighting apparatus comprising: a power conversion unit for converting a DC power supply voltage to a desired voltage; an inverter for inverting a polarity of an output of the power conversion unit and supplying an alternating output to a discharge lamp acting as a load; a lamp voltage detection unit for detecting a voltage value corresponding to a tube voltage of the discharge lamp; a lamp current detection unit for detecting a current value corresponding to a tube current of the discharge lamp; and a control unit for controlling an output of the inverter to be supplied to the discharge lamp depending on the detection results of the lamp voltage and lamp current detection units, wherein the control unit comprises electrode heating amount setting means which sets an electrode heating period such that an alternation time of the output power to be supplied to the discharge lamp is made longer than an alternation time in a steady lighting period thereof, and which determines the alternation time of the output power in the electrode heating period when an accumulated value of a lamp current with respect to a time lapse becomes a first predetermined value, and which increases the alternation time in the electrode heating period to be longer than a normal alternation time thereof, depending on a lowering degree of a lamp power or a lamp current supplied to the discharge lamp.