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The most common way to illuminate the liquid crystal layer is to use a cold cathode fluorescent lamp (CCFL). They increase the luminosity of the screen. They are found in laptops, TVs, and other devices with LCDs (photocopy machine display, mobile phones, etc.). CCFLs are classified hazardous due to their mercury (Hg) content and the phosphor layer. The mercury is applied to the fluorescent tubes in a gaseous form. If it is ionised by electricity, it emits UV light, which in turn is transformed by the phosphor layer into visible light.
Two CCFLs are to be found inside the display frame, usually on the upper and bottom parts.
Caution during dismantling
Depollution should be done in a fume hood with an air pollution control system to avoid mercury vapour exposure to the workers when a backlight accidentally breaks.
The fluorescent tubes are very thin and fragile, and should not break during dismantling. Access to them is possible only through careful manual dismantling of the frame. Once it is located, the fluorescent tube can be disconnected easily by cutting the alimentation wires. Be careful, as some fluorescent tubes are, in addition, stuck to the support.
Usually, backlights from TV monitors are more difficult to remove than those in computer monitors, as they are larger. In case of breaking, they should quickly be put into a closed box or barrel.
Caution during storage
Fluorescent tubes should be stored very carefully in boxes that prevent the release of Hg-vapour in case of breaking. However, if possible the breaking of the fluorescent tubes should be avoided.
Source of information
Dismantling Guide for IT Equipment, which was elaborated within the SRI project and financially supported by SECO and UNIDO, June 2015