» LED Backlighting - the Advantages

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March 7, 2008

LED Backlighting - the Advantages

LED backlighting technology has numerous advantages over the conventional mercury-arc lamps CCFL (cold cathode fluorescent tube). Advantages include:

LCD Blur Reduction

LCD displays have a greater motion blur effect primarily because an LCD pixel remains lit, unlike the CRT phosphor screens which are strobed for a very short time. LCD manufacturers have combated motion blur by increasing the refresh rate to 120Hz. Mitsubishi have called their technology Smooth120Hz, Sony have Motion Flow, Toshiba has ClearFrame, LG – TruMotion Drive and JVC call it Clear Motion Drive II. The televisions video processor creates an interpolated frame between each existing frame to achieve 120Hz and make motion appear smoother for the viewer.

Motion blur of LCDs can also be reduced by using LED backlighting. For example Samsung’s 81 series LCD HDTV have “Motion Plus,” a scanning technology that strobes the horizontal rows of LEDs progressively from top to bottom. Of note to gamers should be that this approach is superior in reducing computer generated motion blur introduced by video games.

Improved Dynamic Contrast Ratio – Blacker Blacks

Samsung utilizes multiple LED backlights to vary the backlighting across the LCD screen based on the image displayed. The technique produces improved contrast, stronger blacks and whites and a greater range of graduation between them. Samsung call the technology LED Local Dimming. However, consumers should be careful not to base television choice on just the highest dynamic contrast ration which seems to be a competition point between manufacturers. It’s much like the mega-pixel count with cameras at the moment. Read PTek’s technology guide on contrast ratio for more information.

Improved (larger) Color Gamut for more Lifelike Images

An advantage of LED backlighting is its provision of a wider color gamut compared to CCFL backlit LCD televisions. LED’s cover a broader range of red and greens up to 114% of the NTSC standards. With being able to display a more extensive range of colors, comes the attribute of colors being more natural or lifelike as they are closer to the human eye’s color perception range.

Improved Reliability

As they are a solid state semiconductor device, LED have a longer lifespan typically lasting over 100,000 hours. Being solid state devices, LED will perform exactly as when they were manufactured as opposed to CCFL which loose light output continuously over their life - up to 50%.

Lower Power Consumption

LED backlights have a lower power consumption than traditional backlighting sources. LED manufacturer, Luminus, quotes 60% reduction in power consumption for LED backlighting compared to conventional mercury-arc lamps.

Environmental Benefits

The significant lower power requirements of LEDs equate to reduced air pollution from carbon emissions.

The longer life span of 100,000 compared to around 20,000 for CCFL saves resources through being replaced less often.

Conventional CCFL backlights contain some mercury leaving a safe disposal problem. LED lighting can be manufactured to conform to the European Union’s RoHS initiative to restrict the use of certain hazardous substances in electrical and electronic equipment. The Directive bans the placing on the EU market of new electrical and electronic equipment containing more than agreed levels of lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyl (PBB) and polybrominated diphenyl ether (PBDE) flame retardants.