Mercury-type cold cathode fluorescent lamps (Hg-CFLs) are widely used as light sources of LCD backlighting for car-navigations. A mercury-free backlight in which Xe-type small diameter CFLs are installed, has been developed. A 7 inch-size backlight was evaluated. Luminance of the backlight is 6,OOO cd/m2 at 6.5 W. And this backlight has stable light output, rapid light output response and wide dimming capability over the wide temperature range. Therefore, it is suitable for a car-navigation display. As far as the backlighting for a car navigation is concerned, a compact dimension and a stable light output over the wide temperature range tram -40 grad C to 85 grad C, are required. The structure of a Xe-CFL in the approach has an outer diameter of the glass tube of 2.4 mm. R, G, B tri-phosphor is coated on the inner wall of the glass tube. The mixture of xenon and neon (Xe:Ne=70:30). Electrodes consist of one inner electrode and one outer electrode. The inner electrode is the same structure as one for a conventional Hg-CFL. The outer electrode is made of a thin metal wire. It is coiled around the glass tube and is fixed by the transparent shrinking tube. Structure of the mercury-free backlight. At the present time, luminous efficiency of the CFL is about 60 % as much as that of a HG-CFL. So, the mercury-free backlight needs twice as many CFLs as the conventional Hg-CFL backlight. The dimension of the backlight is wide 7 inch. Two lamps are arranged at both side of a light guide plate. Total 4 lamps are installed. The light emitting surface is equipped with a prism sheet and a diffuser sheet. The thickness of backlight is 10 mm.
A mercury-free CFL backlight for car-navigation display
Eine quecksilberfreie Hintergrundbeleuchtung Navigationsbildschirms im Auto
2002
5 Seiten, 9 Bilder, 1 Tabelle, 3 Quellen
Conference paper
English
A mercury-free CFL backlight for car-navigation display
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