DISCHARGE LAMP OPERATION DEVICE AND ILLUMINATION DEVICE

摘要

In order to enhance stability of a discharge lamp at the time of dimming lighting even in the case where a light output is lowered, a direct current superimposing circuit 1 superimposes a direct current voltage on an alternating current voltage applied to a fluorescent lamp FL, and a dimming signal correction circuit K1 receives a detection value of a direct current voltage detection circuit 2 and a dimming signal Vs1 that is from an outside, outputs a dimming signal Vs0 higher in level than the dimming signal Vs1 in the case where the detection value of the direct current voltage detection circuit 2 exceeds a first threshold value Vth1, and decreases the level of the outputted dimming signal Vs0 to the level of the inputted dimming signal Vs1 in the case where the detection value of the direct current voltage detection circuit 2 falls down below a second threshold value Vth2 that is equal to or less than the first threshold value Vth1. Then, an amount of alternating current power supplied to the fluorescent lamp FL by an inverter circuit INV is increased and decreased in response to fluctuations of the level of the dimming signal Vs0 outputted by the dimming signal correction circuit K1, whereby the fluorescent lamp FL is dimmed.