Kylmäkatodivalaisin

Kylmäkatodivalaisin, also known as a cold cathode fluorescent lamp (CCFL), is a type of gas-discharge lamp. Unlike hot cathode fluorescent lamps, CCFLs do not require a heated filament to initiate the discharge. Instead, they use a high voltage to ionize the gas within the tube, which then emits ultraviolet (UV) light. This UV light strikes a phosphor coating on the inside of the tube, causing it to fluoresce and produce visible light.

CCFLs are characterized by their compact size and ability to operate at a wide range of temperatures. They were commonly used as backlights for liquid crystal displays (LCDs) in laptops, monitors, and televisions before the widespread adoption of LED backlighting. Their applications also extended to decorative lighting, signage, and specialized scientific instruments.

The operation of a CCFL involves a low-pressure inert gas, often a mixture of argon and neon, and a small amount of mercury vapor. When a high voltage is applied across the electrodes at each end of the tube, an electrical discharge occurs through the gas. This discharge excites the mercury atoms, causing them to emit UV photons. The phosphor coating then converts these UV photons into visible light.

While CCFLs were once prevalent, they have largely been superseded by light-emitting diodes (LEDs) in many applications due to the latter's superior energy efficiency, longer lifespan, thinner profiles, and better color control. However, CCFLs may still be found in older electronic devices or in niche applications where their specific characteristics are advantageous.