Patent ID: 8008868

Claim:
A discharge lamp lighting apparatus comprising: a power control circuit that outputs a DC current; an AC conversion circuit to which the DC current is inputted, the AC conversion circuit reversing a polarity of the DC current at predetermined timings to produce and output a discharge lamp driving AC current; and a controller configured to control the AC conversion circuit to perform an AC conversion control for controlling the timings at which a polarity of the discharge lamp driving AC current is reversed and configured to control the power control circuit to perform a current control for controlling a magnitude of the DC current, wherein the controller changes an accumulated energy supplied to each electrode of a discharge lamp in one cycle of the discharge lamp driving AC current in accordance with a periodic pattern, the periodic pattern includes a plurality of segmented periods during each of which the accumulated energy is maintained at a same level for a plurality of cycles of the discharge lamp driving AC current, and a level of the accumulated energy in at least two of the segmented periods differ from each other, and the controller performs the current control by externally receiving a power control signal and setting an average of the DC current in a section that corresponds to the one cycle of the discharge lamp driving AC current to a current magnitude that corresponds to the power control signal, and controlling a magnitude of the accumulated energy in relation to the average value of the DC current.