Mercury‐free, high‐luminance and high‐efficacy flat discharge lamp for LCD backlighting

Abstract

Abstract The liquid‐crystal displays having a 4‐ to 7‐inch diagonal used in car navigation systems demand strict conditions of at least 10,000 cd/m 2 luminance and a –30 to 80 °C operating temperature range for backlights for use in a variety of environments. To satisfy these conditions, a flat discharge lamp that offered high luminance, high efficiency, and a high degree of balance was developed by employing a simple structure that used a rare gas instead of mercury, which has a strong temperature dependence. Narrowing the pulse width of the drive voltage pulse and limiting the amount of current made it possible to obtain uniform emitted light that spreads throughout the entire discharge space. When the maximum luminance of 9200 cd/m 2 was obtained, the emission efficiency was 20.4 lm/W. When the luminance was 1080 cd/m 2 , the maximum emission efficiency of 34.1 lm/W was achieved. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(8): 55–63, 2001