LEDbacklights

LED backlights are a lighting system that uses light-emitting diodes as the source for illuminating a display, typically a liquid crystal display. In such devices, LEDs are placed either along the edges of the panel (edge-lit) or directly behind the active area (direct-lit or full-array). Light is distributed using a light guide plate and diffusion/brightness enhancement films to create a uniform field behind the LCD while allowing the liquid crystal layer to control image brightness and color.

An edge-lit configuration uses long strips of LEDs at the panel edge, delivering light across the panel with a light guide plate; direct-lit uses a grid of LEDs behind the screen for better uniformity and local dimming options. A newer approach, mini-LED, uses many small LEDs to improve local dimming and contrast.

LED backlights offer advantages over earlier CCFL backlights, including higher energy efficiency, longer operating life (often 50,000–100,000 hours), thinner panel profiles, and lower heat generation. They also enable wider color-gamut performance and adjustable color temperature through drive current control. Typical color temperatures are around 6500K, with CRI values commonly in the 80s or higher for high-quality displays.

Challenges include uniformity across the panel, occasional brightness nonuniformities or hot spots, aging of LEDs leading to color or brightness shifts, flicker from certain drive schemes, and higher upfront cost for some configurations. Design strategies such as full-array backlighting with local dimming, diffusion layers, and precise current regulation address these issues.

Applications span televisions, computer monitors, laptops, and mobile devices, where thin profiles and energy efficiency are valued.