How does LED TV Work?

by Jack Burden

If you pay any attention to televisions then you've certainly heard of a "new" TV technology called LED TV. New is in quotes because LED TV is a bit of a misnomer, and LED TV should technically be called and LED back lit LCD TV, the panel is still an LCD panel but the back light is provided by Light Emitting Diodes (LED) rather than the Cold Cathode Fluorescent Lamps found in the televisions manufacturers are still calling LCD TVs.

While calling it a new TV technology is a bit of a stretch there are advantages to using LEDs to light an LCD panel. LED lights produce a brighter, truer white than CCFL so LED TVs naturally have a higher contrast than using a CCFL to light the same LCD panel would. They also use less energy than CCFL so your power bill will be lower, even if it's only a minuscule amount.

LEDs are also very small, this allows for construction of very thin televisions, especially when the LEDs are located around the edge of the panel rather than behind it. Most of the sub 1 inch depth LED TVs use edge lighting. Edge lighting has some disadvantages though, many of the edge lit televisions we have seen don't have the light uniformity of a back lit television. For regular viewing this often isn't apparent but display a uniform, medium gray image file onto the screen and you can see hot and dark spots quite clearly.

Another advantage of LED back lighting is full array local dimming. For this the LCD panel is back lit by by many banks of LEDs that can be individually controlled by software inside the televisions. In an image with light and dark areas the amount of back lighting is dimmed or brightened to heighten contrast and show black levels that are much, much higher than CCFL back lit LCD TVs. Not quite to the black levels of plasma this is still a major improvement over CCFL, LED edge lighting or non dimming LED back lighting. If you are in the market for an LED TV this is probably the number one feature we would recommend looking for.

In summary, LED TV is not a brand new television technology as some manufacturers or sales people would have you believe but it is quite an improvement over traditional CCFL back lighting.