Patent ID: 7973493
Filing Date: 2011-07-05
Classification: H05B

Abstract:
1. A discharge lamp lighting device that dims a discharge lamp by increasing or decreasing an amount of supplied power to the discharge lamp in response to fluctuations of a level of a dimming signal, comprising: an alternating current output circuit that supplies alternating current power to the discharge lamp; a direct current superimposing circuit that superimposes a direct current voltage on an alternating current voltage applied to the discharge lamp; a direct current voltage detection circuit that detects a direct current voltage component of a voltage generated on both ends of the discharge lamp; a dimming signal correction circuit that receives a detection value of the direct current voltage detection circuit and a dimming signal that is from an outside, outputs a dimming signal higher in level than the inputted dimming signal in a case where the detection value of the direct current voltage detection circuit exceeds a first threshold value, and decreases the level of the outputted dimming signal to the level of the inputted dimming signal in a case where the detection value of the direct current voltage detection circuit falls down below a second threshold value that is equal to or less than the first threshold value; and a control circuit that dims the discharge lamp by increasing or decreasing an amount of the alternating current power in response to fluctuations of the level of the dimming signal outputted by the dimming signal correction circuit, the alternating current power being supplied to the discharge lamp by the alternating current output circuit.