CCFL

CCFL stands for cold cathode fluorescent lamp, a type of fluorescent lamp that uses cold cathodes and a mercury-containing gas discharge to generate ultraviolet light, which is converted to visible light by a phosphor coating. In liquid-crystal displays and some signage, CCFL tubes serve as the backlight behind the image panel. Typical CCFL backlights comprise slender glass tubes filled with an inert gas and mercury, with a phosphor-lined inner surface that emits white light when excited.

Operation relies on an electronic inverter to provide high-voltage alternating current to the tubes. The inverter delivers an initial strike voltage to start the discharge and then sustains the light at a lower, high-frequency voltage. Because the cathodes are not heated, CCFLs are classified as cold-cathode devices. Light color depends on the phosphor mix and the gas composition, commonly yielding cool white or neutral white light in the 5000–6500 K range. Uniform backlighting is achieved through multiple tubes and optical diffusion layers arranged behind the LCD panel.

CCFLs offered advantages such as relatively good color rendering, compact form factors for thin displays, and moderate brightness. They also required no external hot-filament heating. However, they contain mercury and rely on voltage-intensive inverters, can suffer brightness drift with temperature, and are more challenging to dim smoothly. Their adoption declined as LED-based backlighting became dominant due to higher efficiency, longer life, narrower form factors, and simpler dimming.

Typical lifetimes range from about 20,000 to 40,000 hours, though individual performance varies with usage and temperature. Disposal and recycling considerations arise from mercury content. CCFL technology is now largely legacy in consumer displays, with LEDs replacing most applications.