| 摘要 |
PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device suppressing power variation with respect to the change of a lamp lighting state, and preventing the occurrence of difference in flicker suppression effect by a current pulse. SOLUTION: If the frequency of a lamp current is changed when a discharge lamp 16 is being normally lit by a lamp current h, a superposition period of a current pulse superposed on the last half of a half cycle of the lamp current i of rectangular waves for suppressing flicker is varied in line with the change of the frequency of the lamp current. That is to say, a control circuit 18 execute control to vary the generation time of a current pulse B carried by being superposed on the half cycle A of the lamp current of rectangular waves flowing to the discharge current 16 based on the change of the frequency of the lamp current i from the outside, and to stabilize the ratio of an area B of the current pulse superposed on the lamp current to an area A of the half cycle of the lamp current. Thereby, the variation of power with respect to the change of the lighting state of the discharge lamp 16 can be restrained, and the difference in the effect suppressing flicker can be suppressed. COPYRIGHT: (C)2009,JPO&INPIT |
