Patent ID: 7847492
Filing Date: 2010-12-07
Classification: H05B,Y02B

Abstract:
1. A discharge lamp lighting apparatus, comprising: a power supply circuit that supplies power to a discharge lamp; a lamp voltage detection circuit that detects lamp voltage of the discharge lamp so as to output a lamp voltage detection signal; a lamp current detection circuit that detects lamp current of the discharge lamp so as to output a lamp current detection signal; an electric power control circuit that updates a lamp current detection signal so that, according to the lamp voltage detection signal, a value of a load electric power value (PL) which is applied to the discharge lamp agrees with that of a predetermined target electric power value (PT); an electric power supply capacity control circuit that controls the power supply circuit in a feed back manner so that a difference between the lamp current detection signal and the lamp current target signal becomes small; a lamp current modulation circuit which is used for carrying out increase modulation on lamp current with a pulse according to a modulation signal, wherein at a start-up of the discharge lamp or immediately thereafter, the increase modulation is restrained, and in a lighting steady state of the discharge lamp, the restraining of the increase modulation is released, and wherein when the restraining of the increase modulation is released, in a transition period from immediately after the start-up of the discharge lamp to the lighting steady state, the restraining of increase modulation is gradually released.