Mercury-free, high-luminance and high-efficacy flat discharge lamp for LCDbacklighting

The liquid-crystal displays having a 4- to 7-inch diagonal used in car navi gation systems demand strict conditions of at least 10,000 cd/m(2) luminanc e and a -30 to 80 degreesC operating temperature range for backlights for u se in a variety of environments. To satisfy these conditions, a flat discha rge 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 t he pulse width of the drive voltage pulse and limiting the amount of curren t 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 108 0 cd/m(2), the maximum emission efficiency of 34.1 lm/W was achieved. (C) 2 001 Scripta Technica, Electron Comm Jpn.