Patent ID: 7598678

Claim:
A lamp lighting apparatus comprising: a lamp light means for applying an AC rectangular wave to a discharge lamp so as to light the discharge lamp, said lamp light means including a DC power supply, a DCDC converter for adjusting an output of said DC power supply, and an inverter for converting an output of said DCDC converter into the AC rectangular wave; an arc spot movement detecting means for monitoring an electric parameter of said lamp light means so as to detect a movement of an arc spot lying within a band of frequencies higher than a critical flicker frequency; and an arc spot movement suppressing means for, when said arc spot movement detecting means detects a movement of the arc spot, controlling the AC rectangular wave applied to said discharge lamp by said lamp light means according to a detection signal indicating the detection of the movement of the arc spot from said arc spot movement detecting means so as to perform a process of suppressing the movement of the arc spot.