Patent ID: 8853961

Claim:
A discharge lamp lighting device comprising: a discharge lamp driving section that drives a discharge lamp by supplying a driving current to the discharge lamp; and a control unit that controls the discharge lamp driving section, wherein the control unit alternately performs a first-interval DC driving process and a first-interval AC driving process in a first interval, alternately performs a second-interval DC driving process and a second-interval AC driving process in a second interval other than the first interval, controls a first DC current that is configured by a first polarity component starting from a first polarity so as to be supplied as the driving current in the first-interval DC driving process, controls a first AC current that repeats the first polarity component and a second polarity component so as to be supplied as the driving current in the first-interval AC driving process, controls a second DC current that is configured by the second polarity component starting from a second polarity so as to be supplied as the driving current in the second-interval DC driving process, controls a second AC current that repeats the first polarity component and the second polarity component so as to be supplied as the driving current in the second-interval AC driving process, and changes a length of at least one of a period during which the first-interval DC driving process is performed and a period during which the second-interval DC driving process is performed, so as to be shortened in a stepped manner within a predetermined sub-interval.