| 摘要 |
PURPOSE:To start a lighting even when a dimming quantity is set less than a rating by controlling a power control means according to a determined first characteristic for lighting start before lighting, in a lighting control device, and switching the control characteristic of the power control means from the first characteristic to a second characteristic after lighting. CONSTITUTION:The alternate current from a commercial AC power source 10 is converted to a direct current and inputted to a chopper circuit 40 through a smoothing capacitor 25. The ON/OFF signal formed by a chopper control circuit 130 is inputted to the circuit 40, and the output from this is inputted to an inverter circuit 70 through a DC reactor 50 and a smoothing capacitor 26. Thereafter, in the circuit 70, the direct current is converted into a rectangular wave alternate current having a determined frequency, and then supplied to a high pressure discharge lamp 100. The control of the current value at this time is conducted by changing the set value of an output luminance regulator 120. Thus, the regulation of the power quantity by a power regulating device 1 is carried out only by the current control by the circuit 40, and only the current level value is changed without carrying out the frequency control by the circuit 70 to eliminate the superposition of dead time which causes a lighting failure. |
