| 摘要 |
PROBLEM TO BE SOLVED: To provide a device for saving on power of a high pressure discharge lamp through the phase control of a power conditioning element while causing no lighting failure of the high pressure discharge lamp when a power-saving rate is changed, and reducing the load of a starting current on the power conditioning element right after a power supply is input.SOLUTION: The power-saving device 11 for the high pressure discharge lamp 13 is equipped with: a triac 14 for controlling power to be supplied from the AC power supply 12 to the high pressure discharge lamp 13, a control circuit 18 for controlling a conduction timing for the triac 14; a setting circuit 15 for setting the power-saving rate, a circuit 16 for detecting the zero cross of a voltage waveform; and a storage circuit 17 for storing the conduction timing for the triac 14 in relation to the voltage zero cross. The control circuit 18 energizes a relay 20 right after the power supply is input, and starts the phase control of the triac 14 after the starting current is stabilized. In the phase control, the control circuit 18 changes the conduction timing at a relatively sharp gradient when a variation of the power-saving rate is smaller, and changes the conduction timing at a relatively gentle gradient when the variation of the power-saving rate is greater, thus preventing the flickering and going-out of the high pressure discharge lamp 13. |
