Patent ID: 7202611

Claim:
A discharge lamp lighting device for lighting a discharge lamp, comprising: a drive circuit connectable to the discharge lamp to feed alternating power having high frequency to the discharge lamp, thereby flowing a lamp current through the discharge lamp; and a control circuit for generating a drive pulse to drive the drive circuit to perform a burst dimming control over the discharge lamp, thereby alternately appearing a lighting time period for lighting the discharge lamp and a lights-off time period for turning off the discharge lamp, wherein the control circuit comprises: detecting means for detecting the lamp current; subtracting means for subtracting the detected lamp current from a reference value to obtain a difference therebetween as an output; a digital filter operating as an integrator to integrate the output of the subtracting means to obtain an output; and pulse generating means for generating the drive pulse based on the output of the digital filter, the lighting time period comprises a first time period immediately after a start of the lighting time period and a second time period following the first time period, the second time period being longer than the first time period; the control circuit sets the reference value to a target current value in the second time period, the control circuit increase the reference value in the first time period to the target current value until an end of the first time period, the digital filter retains the output obtained at an end of the lighting time period until a next lighting time period starts, the control circuit adjusts the lamp current to the target current value during the lighting time period.