| 摘要 |
PURPOSE:To simply constitute a control circuit by controlling only the peak value of the current flowing in a semiconductor switching element and the constant switching cycle. CONSTITUTION:When a switch is closed, a current is fed to a discharge lamp 1 from an AC power source 2 via a noise filter circuit 13, a rectifying/smoothing circuit 11, a chopper circuit 3, and a smoothing circuit 10. When a semiconductor switching element 31 is turned on, a current detector 5 detects only the current flowing in it, a control circuit 4 receives the signal from the current detector 5, and it detects the peak current value in one pulse of the semiconductor switching element 31 and the constant switching cycle to control the constant power. This device can be constituted with a simple control circuit 4. |
