Patent ID: 8324828

Claim:
A high-pressure discharge lamp lighting device that supplies an alternating current to a high-pressure discharge lamp to cause lighting, the high-pressure discharge lamp having an arc tube in which a halogen material is enclosed and a pair of electrodes is disposed opposite to each other, each electrode having a protuberance at a tip thereof, comprising: a frequency switch unit operable to switch a frequency of the alternating current to be supplied to the high-pressure discharge lamp among (i) a first frequency, (ii) a second frequency greater than the first frequency, and (iii) a third frequency smaller than or equal to the first frequency; and a control unit operable to control the frequency switch unit so that (a) a time period A, in which the alternating current of the third frequency is supplied, occurs at the beginning of each of predetermined time intervals, and (b) a remainder of each of the predetermined time intervals includes (i) a time period B, in which the alternating current of the first frequency is supplied, and (ii) a time period C, in which the alternating current of the second frequency is supplied, the time period B and the time period C being alternately repeated, wherein the time period A is longer than the time period B, and has a length corresponding to a predetermined number of cycles of the alternating current of the third frequency, ranging from 5.5 to 50 cycles inclusive.