LEDbacklight

LED backlight is a form of illumination used in most modern LCD displays, where light-emitting diodes provide the light behind or around the liquid crystal layer. LED backlights replaced CCFLs due to higher efficiency, more compact form factors, and longer lifespans. Common architectures are edge-lit and direct-lit (full-array). In edge-lit designs, LEDs line the display’s edge and light is distributed across the panel via a light guide plate and diffusion films. Direct-lit or full-array backlighting places LEDs behind the screen, enabling more uniform brightness and, in many cases, local dimming.

Operation: The liquid crystals modulate the backlight to form images. LEDs can be white or color-tunable; in many sets, white LEDs are used with color filters, while some systems use RGB LEDs with phosphor to produce broad color. Full-array backlights may support local dimming, where brightness in zones is independently controlled to improve contrast, particularly in dark scenes.

Advantages include higher energy efficiency, thinner and lighter panels, reduced heat, and longer lifespans compared with CCFLs. LED backlights can achieve higher peak brightness and cover wider color gamuts; local dimming in full-array systems improves black levels and perceived contrast.

Disadvantages: higher initial cost than CCFL, more complex manufacturing, and potential uneven brightness in edge-lit designs. Some users detect PWM flicker at certain brightness levels. Color stability and uniformity depend on LED quality and aging. Modern designs mitigate these issues with better diffusion and local dimming.

Applications: LCD televisions, computer monitors, laptops, tablets, and other devices using LCD panels. In recent years, higher-density LED arrays and mini-LED backlights have been used to approach higher contrast levels and dynamic range.