An LED-backlit LCD is a liquid-crystal display that uses light-emitting diodes (LED) for backlighting instead of cold cathode fluorescent lamps (CCFL). LED-backlit displays use the same TFT (thin-film transistor) LCD technologies as CCFL-backlit LCDs, but offer a variety of advantages over them. The LED bulbs are typically blue or white, but more recently RGB ones have been developed. There are four types of LED-backlit LCDs: Edge-Lit, Direct-Lit, Full-Array Local Dimming (FALD) and Mini-LED, each describing how the LED bulbs are arranged behind the liquid-crystal display for illumination. A variant is QLED, a type of LED-backlit LCD that uses an extra layer film of quantum dots for improved color gamut. Televisions that use a combination of an LED backlight with an LCD panel are sometimes advertised as LED TVs, although they are not truly LED displays. They largely replaced CCFL-backlit LCD TVs in sales and manufacture by the early 2010s. Backlit LCDs of any type cannot achieve true blacks for pixels, unlike the totally self-emissive OLED and MicroLED displays. This is because even in the "off" state, black pixels still allow some light from the backlight through. Some LED-backlit LCDs use local dimming zones to increase contrast between bright and dim areas of the display, but this can result in a "blooming" or "halo" effect on dark pixels in or adjacent to an illuminated zone.
Comparison with CCFL-backlit LCDs
Advantages When compared with earlier CCFL backlights, using LEDs for backlighting offers:
Wider color gamut (with RGB-LED or QDEF) and dimming range Greater contrast ratio Very slim (some screens are less than 0.5 inches (13 mm) thin in edge-lit panels) Significantly lighter and cooler, as much as half the total chassis and system weight of a comparable CCFL Typically 20–30% lower power consumption and longer lifespan Greater reliability
Disadvantages Light is not evenly lit thus creating potential bright hot spots or dark patches on a screen
LED arrangements
LED backlights replace CCFL (fluorescent) lamps with a few to several hundred white, RGB or blue LEDs. An LCD with LED-Backlight may be edge- or direct-lit:
edge-lit (ELED): LEDs form a line around the rim of the screen. May additionally support: frame dimming: adjusts the brightness of the entire backlight based on the content displayed, as if local dimming was supported but only with a single zone local dimming: multiple vertical or horizontal zones are individually controlled direct-lit (DLED) or full-array: LEDs form an array directly behind the screen at equally spaced intervals. May additionally support: frame dimming: adjusts the brightness of the entire backlight based on the content displayed, as if local dimming was supported but only with a single zone local dimming: multiple direct-lit LED clusters (rectangles) are individually controlled. Commonly referred to as Full Array Local Dimming (FALD). Additionally a special diffusion panel (light guide plate, LGP) is often used to spread the light evenly behind the screen. The local dimming method of backlighting allows to dynamically control the level of light intensity of specific areas of darkness on the screen, resulting in much higher dynamic-contrast ratios, though at the cost of less detail in small, bright objects on a dark background, such as star fields or shadow details. A 2016 study by the University of California (Berkeley) suggests that the subjectively perceived visual enhancement with common contrast source material levels off at about 60 LCD local dimming zones. In 2025 RTINGS.com found in accelerated longevity tests that edge-lit TVs were more prone to quicker failure than direct-lit panels (especially during non-stop usage) due to the heat of the LEDs being more concentrated and intense than direct-lit panels, making them more prone to panel cracking and warping and thus LED burnouts and failures.
… excerpt ends here. Continue reading the full article.
