The term Cold Cathode Fluorescent Lamp (CCFL) implies that the cathode of such a tube is not heated, it remains "cold". Cold cathode lamps are fluorescent lamps in which the electrons are emitted from the unheated cathode by a strong electric field formed in front of the cathode.
The surface of the cathode is such that it generates many secondary electrons which flow to the anode via the accelerating voltage applied to the anode. The accelerating voltages are much higher than those of heated cathode tubes. Most cold cathode tubes are filled with an ionizing gas that emits light when it collides with the electrons.
Cold cathode tubes use various gases such as neon or krypton for light emission. They are used in outdoor advertising, lighting and computer technology. Here, it is the Cold Cathode Fluorescent Lamps (CCFL) that are used for backlightingLCD displays. These tubes are thin white luminescent fluorescent lamps, which have an areal structure and illuminate the LCD displays from behind. CCFLs also exist as point light sources whose light is evenly distributed via diffusers for backlighting. The color spectrum of CCFL light sources does not sufficiently harmonize with the color filters of the LCD display and therefore restricts the color space of LCD displays.