Luminance and Luminous Efficacy Improvement of Mercury-Free Flat Fluorescent Lamp With Arclike Electrode

A mercury-free flat fluorescent lamp with an arclike electrode is developed to improve luminance and luminous efficacy and to prevent discharge contraction. The influences of the rising time of a driving waveform and the gas mixture under different gas pressures on luminance and luminous efficacy are studied. The experimental results show that the luminance and luminous efficacy increase as the gas pressure and Xe content increase. The luminance of about 7500 cd/m² can be achieved at a pressure of 60 kPa with Ne-Xe (30%). The maximum luminous efficacy of the system, including the inverter, is about 23.7 lm/W at a pressure of 50 kPa with Ne-Xe (30%). Compared with the gas mixture of Ne-Xe (30%), when the gas mixture of Ne-Xe (32%)-He (8%) is used, the luminance and ignition voltage increase. In addition, the luminous efficacy for a steep rising edge of a waveform within 400 ns can be increased about 10% higher than that for a gradual rising edge above 800 ns.