A low power consumption fluorescent lamp for LCD backlighting

Summary form only given. A new low power consumption fluorescent lamp, suitable for mobile computing device backlighting, is investigated. Usually efficiency of conventional CCFL (Cold Cathode Fluorescent Lamps) operated in conditions of low power wattage and/or at low ambient temperature decreases because of the deficit of Hg vapor pressure. Containing Xe and Hg in lamps and utilizing UV emissions from both, our new lamp efficiency in above conditions has been much improved. The lamp conditions are as follows. Input wattage is less than 1 watt, typically 0.5 W. Inner diameter is 2 mm, lengths are 45 mm or 100 mm. Gas pressure is more than 7 kPa, typically 9.3 kPa, Xe and Xe-Ar gases are estimated. The lamps are operated in pulse mode: tens kHz and duty-time is less than 50%, typically 20% to increase the efficiency. The pulse mode operation makes lamp efficiency about twice as much as DC operation. With optimizing operating factors, the lamp efficiency below ambient temperature -10/spl deg/C (14/spl deg/F) becomes 60% of the efficiency at 25/spl deg/C (77/spl deg/F), on the other hand, in the case of conventional CCFL, about 20% of the efficiency at 25/spl deg/C (77/spl deg/F). The efficiency becomes higher than that of conventional CCFL when input lamp wattage is less than 0.07 W/cm. Because of the high gas pressure, afterglow from Xe/sub 2/ is hidden in the decay of the emission from the phosphor which decay time is /spl sim//spl mu/sec. However, our model calculation results show Xe/sub 2/ excimer emissions contribute to its high efficiency.