Technology
LED-backlit LCDs are not self-illuminating (unlike pure-LED systems). 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). Variations in LED backlighting offer different benefits. 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. 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. Unwanted bleed-through channels do not "whiten" the desired color as much, resulting in a larger gamut. RGB LED technology continues to be used on Sony BRAVIA LCD models.
LED backlighting using “white” LEDs produces a broader spectrum source feeding the individual LCD panel filters (similar to CCFL sources), resulting in a more limited display gamut than RGB LEDs at lower cost. A dynamic “local dimming” LED backlight was first demonstrated by BrightSide Technologies in 2003, and later commercially introduced for professional markets (such as video post-production). Edge LED lighting was first introduced by Sony in September 2008 on the 40-inch (1,000 mm) BRAVIA KLV-40ZX1M (known as the ZX1 in Europe). Edge-LED lighting for LCDs allows thinner housing; the Sony BRAVIA KLV-40ZX1M is 1 cm thick, and others are also extremely thin.
LED-backlit LCDs have longer life and better energy efficiency than plasma and CCFL LCD TVs. Unlike CCFL backlights, LEDs use no mercury (an environmental pollutant) in their manufacture. However, other elements (such as gallium and arsenic) are used in the manufacture of the LED emitters; there is debate over whether they are a better long-term solution to the problem of screen disposal.
Because LEDs can be switched on and off faster than CCFLs and can offer a higher light output, it is theoretically possible to offer very high contrast ratios. They can produce deep blacks (LEDs off) and high brightness (LEDs on). However, measurements made from pure-black and pure-white outputs are complicated by the fact that edge-LED lighting does not allow these outputs to be reproduced simultaneously on screen.
In September 2009 Nanoco Group announced a joint development agreement with a major Japanese electronics company, under which it will design and develop quantum dots for LED backlights in LCDs. Quantum dots are useful in displays, because they emit light in specific, normal distributions. This can result in a display that more accurately renders colors in the visible spectrum. Other companies are also developing quantum dots for displays: Nanosys, 3M, QD Vision of Lexington, Massachusetts and LG Display of South Korea.
Read more about this topic: LED-backlit LCD Display
Famous quotes containing the word technology:
“Radio put technology into storytelling and made it sick. TV killed it. Then you were locked into somebody else’s sighting of that story. You no longer had the benefit of making that picture for yourself, using your imagination. Storytelling brings back that humanness that we have lost with TV. You talk to children and they don’t hear you. They are television addicts. Mamas bring them home from the hospital and drag them up in front of the set and the great stare-out begins.”
—Jackie Torrence (b. 1944)
“If the technology cannot shoulder the entire burden of strategic change, it nevertheless can set into motion a series of dynamics that present an important challenge to imperative control and the industrial division of labor. The more blurred the distinction between what workers know and what managers know, the more fragile and pointless any traditional relationships of domination and subordination between them will become.”
—Shoshana Zuboff (b. 1951)
“Our technology forces us to live mythically, but we continue to think fragmentarily, and on single, separate planes.”
—Marshall McLuhan (1911–1980)