| 摘要 |
PROBLEM TO BE SOLVED: To provide electric discharge lamp lighting equipment which can be designed easily for avoiding acoustic resonance phenomenon, even though the calorific value of a chopper circuit is suppressed. SOLUTION: In a period after lighting of an electric discharge lamp DL, a control circuit 4 controls the chopper circuit 1, so that constant electric power is supplied from the chopper circuit 1 in a period which it is in the lower limit voltage or higher of a fixed electric power control range. Moreover, the control circuit 4 chooses a continuing control mode which controls a switching element Q1, so that idle period does not occur in flowing current in an inductor L1 in that period, in which it is below the mode change voltage set up to the minimum voltage or lower of an electric power stopping control range. Furthermore, the control circuit 4 chooses a discontinuing control mode, which controls the switching element Q1 so that the idle period occurs in current flowing in an inductor L1, in a period in which the output voltage of the chopper circuit 1 exceeds the mode change voltage. |
