| 摘要 |
PURPOSE:To simply constitute circuits by detecting only the peak value of the current flowing in the switching element of a chopper circuit and the switching cycle. CONSTITUTION:A chopper circuit 3 with the first switching element 31 connected to a DC power source 6, a current detector 5 detecting the current flowing in the first switching element 31, and a chopper drive control circuit 4 on/off- controlling the first switching element 31 at a high frequency based on the signal of the current detector 5 are provided. The chopper drive control circuit 4 detects the peak current value in one pulse of the first switching element 31, it turns off the first switching element 31 when the preset peak value is attained, these actions are repeated at a fixed cycle, and the lighting of a discharge lamp 1 is constant-power-controlled. This device can be constituted with the simple control circuit 4. |
