![]() ![]() Unwanted bleed-through channels do not "whiten" the desired color as much, resulting in a larger gamut. This was possible because red, green and blue LEDs have sharp spectral peaks which (combined with the LCD panel filters) result in significantly less bleed-through to adjacent color channels. The first commercial full-array LED-backlit LCD TV was the Sony Qualia 005 (introduced in 2004), which used RGB LED arrays to produce a color gamut about twice that of a conventional CCFL LCD television. Variations in LED backlighting offer different benefits. ![]() ![]() There are several methods of backlighting an LCD panel using LEDs, including the use of either white or RGB (Red, Green, and Blue) LED arrays behind the panel and edge-LED lighting (which uses white LEDs around the inside frame of the TV and a light-diffusion panel to spread the light evenly behind the LCD panel). LED-backlit LCDs are not self-illuminating (unlike pure-LED systems). Ī 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. 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. Commonly referred to as Full Array Local Dimming (FALD).Īdditionally a special diffusion panel (light guide plate, LGP) is often used to spread the light evenly behind the screen. local dimming: multiple direct-lit LED clusters (rectangles) are individually controlled.direct-lit (DLED) or full-array: LEDs form an array directly behind the screen at equally spaced intervals.local dimming: multiple vertical or horizontal zones are individually controlled.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.edge-lit (ELED): LEDs form a line around the rim of the screen.An LCD with LED-Backlight may be edge- or direct-lit: LED backlights replace CCFL (fluorescent) lamps with a few to several hundred white, RGB or blue LEDs. LED arrangements a single direct LED cluster of a LCD This can be considered a disadvantage compared to CCFL-backlit LCDs however, if the display allows for the local dimming algorithm to be disabled via software, doing so will remove any blooming at the cost of negating some of the display's contrast-enhancing capabilities. 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. Unlike OLED and microLED displays, LCDs cannot achieve true blacks for pixels which are illuminated by the backlight. Typically 20–30% lower power consumption and longer lifespan.Significantly lighter and cooler, as much as half the total chassis and system weight of a comparable CCFL.Very slim (some screens are less than 0.5 inches (13 mm) thin in edge-lit panels).Wider color gamut (with RGB-LED or QDEF) and dimming range.When compared with earlier CCFL backlights, using LEDs for backlighting offers: Comparison with CCFL-backlit LCDs Advantages While not an LED display, a television using such a combination of an LED backlight with an LCD panel is advertised as an LED TV by some manufacturers and suppliers. LED-backlit displays use the same TFT LCD ( thin-film-transistor liquid-crystal display) technologies as CCFL-backlit LCDs, but offer a variety of advantages over them. For true LED displays, see LED display.Īn Apple iPod Touch disassembled to show the array of white-edge LEDs powered on with the deviceĪn LED-backlit LCD is a liquid-crystal display that uses LEDs for backlighting instead of traditional cold cathode fluorescent (CCFL) backlighting.
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