This year's emerging, evolutionary technology in high-definition televisions is "LED." LED is an abbreviation familiar to consumers, although not in this context. "Light-emitting diodes" are just little lights, though they have significant advantages over other sources of light, advantages that modern technology can now make great use of. LED lamps can shine brighter, live longer, and change colors quicker than other types of illumination. They are also much smaller and use much less energy. In recent years, LED lights have been implemented in everything from cameras (as a flash or source of illumination) to flashlights. Now, enterprising manufacturers are starting to use them in high-definition televisions.
LED is Not OLED
Before we get into what LED TV is, we should first distinguish it from what it isn't. There are a lot of confusing abbreviations in high-definition TV, and it's important to make sure readers aren't confused by similar ones. The LED televisions we're talking about in this article are not "OLED" televisions. OLED stands for "Organic Light-emitting Diode" and is a much more advanced process of television illumination that what we will be discussing here. OLED is often talked about as the future of HDTV, but at present, the technology is still in early development. It's expensive and difficult to make in large quantities and sizes. Right now, the only OLED television on the market is Sony's XEL-1, an 11-inch flat-panel television that costs over $2,500.
The LED televisions we're talking about are those that are designed like traditional LCD televisions, but use LED lights to illuminate the screen instead of older forms of lighting, such as cold-cathode fluorescent lamps.
What is a Backlight?
All LCD televisions are equipped with a backlight that sits behind the screen and shines outward, illuminating the display so it can be viewed at full brightness and intensity. Until recently, that illumination was provided by a cold-cathode fluorescent lamp, similar to the fluorescent lights you're familiar with. The CCFL would shine through the screen with the same intensity across all parts of the screen. The LCD screen's pixels would open and close, allowing light in or blocking it from escaping. It's not a perfect system. Light leaks from around neighboring pixels, so even if a pixel is closed, it doesn't entirely block all the light from escaping. This is why LCD TVs have such difficulty displaying black colors properly.
An LED backlight replaces the evenly-distributed CCFL with an array of small, independent LED lights, which can vary in intensity and cover different parts of the display as needed. This means greater accuracy for colors and contrast, as well as brighter, more brilliant illumination overall. Not to mention the advantages of having a thinner, more energy-efficient flat-panel display.
Edge Lit vs. Local Dimming
There are two different types of LED televisions, however, which consumers should keep an eye out for. The first, most common, and least expensive LED LCD TV uses "edge lighting." Edge-lit LED televisions are illuminated by LED lights that are mounted around the edges of the television's frame, not directly behind the screen. This configuration allows the TV to be extraordinarily thin, but they are incapable of achieving better-than-average contrast ratios as they must illuminate evenly, like CCFLs.
The other type of LED TV is configured with the LED lights directly behind the screen, which allows for a feature called "local dimming." With the LED lights positioned behind the pixels, the TV can use different lighting levels in different areas of the screen. So, if a portion of the image must be light and another portion must be dark, the TV can handle those two portions independently, making the light part bight and the dark part dim, for a more accurate contrast. LED TVs with local dimming are thicker than edge-lit models and more expensive, as well.
Conclusion: A Transitional Stage
As we previously mentioned, the future of HDTV seems to be OLED televisions, which hold even greater potential than these LED-backlit LCD televisions. OLED is still something of a pipe dream, however, and initial prices for the first reasonably-sized consumer models to roll off the assembly line (a year or two years from now) will be astronomically high. For the time being, LED-backlit LCD televisions are the highest-quality high-definition experience available. If you're someone who absolutely must have the best, most cutting edge viewing experience, these televisions are for you. For the average consumer, LED is still a luxury that can be forgone until the prices drop to more attainable levels.