Cold Cathode What are they? A cold cathode fluorescent lamp (CCFL) is a type gas-discharge lamp similar to linear fluorescent or compact fluorescent lamps. CCFLs are used in a number of different specialty applications, such as cold-weather lighting, display back lighting, and signage. They are known for high efficiency, long rated life, and their ability to start in cold conditions. How do they work? A cold cathode lamp functions by using electricity emitted from cathodes to excite mercury vapors using the process of inelastic scattering in order to create fluorescence, just as a typical linear fluorescent does. What sets the cold cathode lamp apart is that by using higher voltage, a cold cathode lamp does not require the cathode to be heated in order to fire and produce light. Where are they used? Cold cathode lamps are used in a number of specialty applications. For many people, the most easily identifiable example of a cold cathode lamp is the neon sign. Cold cathode tubes are also used to backlight signs and LCD displays, they’re probably what is allowing you to be able to read the text on your screen right now, in fact. They are also available in screw in spiral form just like “typical” hot cathode compact fluorescent lamps. CCFL lamps can be used in applications where a lamp will be dimmed or flashed, unlike most of their hot cathode counterparts. They are not known for high light output, so they are best used as secondary lighting or in areas where not much light is needed. Other Helpful Resources Energy Savings Calculator The Light Source - Hot, Hot, Hot!