Patent ID: 7504782
Filing Date: 2009-03-17
Classification: H05B

Abstract:
1. A discharge lamp lighting apparatus which lights up a discharge lamp, comprising: a d.c. power source section which rectifies and smoothes an a.c. voltage and outputs a d.c. voltage; a discharge lamp current detecting circuit which detects a current which flows through said discharge lamp; a discharge lamp voltage detecting circuit which detects a voltage applied upon said discharge lamp; a power source ripple detecting circuit which detects a voltage change of power supplied from said d.c. power source section; and a control circuit which compares a detected voltage which is available from said discharge lamp current detecting circuit with a reference voltage and controls the discharge lamp current so that the discharge lamp current becomes a current corresponding to the reference voltage, wherein said control circuit generates the reference voltage based on the discharge lamp detect voltage detected by said discharge lamp voltage detecting circuit, superimposes the detected voltage change by the power source ripple detecting circuit over the detected voltage which is available from said discharge lamp current detecting circuit, and controls, based on said superimposed voltage change and said reference voltage, an output voltage to said discharge lamp so that said current flowing through said discharge lamp becomes a constant current.