Abstract
The light source of down lighting has been shifted from the high intensity discharge(HID) lamps to the compact fluorescent lamps(CFLs) because the CFLs have many types of light color and show high color rendering. The manufactures of down lighting system have expected new CFLs of high light output that is comparable to that of the lower wattage HID lamps. We have achieved higher light output than that of 100W type conventional HID lamps and reduced the power consumption by 18% by means of the bulb jointing four U-shaped bulbs and the optimal conditions of the lamp current and the bulb diameter. In addition, we have reached to 12000 hours of lamp life, twice the time of 100W type conventional HID lamps, by optimizing the preheat condition of lamp electrodes.
