Explaining Edge-Lit and Full Array Backlighting
It’s why TVs come in "really thin" and "crazy thin"
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Today’s TVs have better picture quality than ever, but without some kind of lighting inside the TV there wouldn’t be any picture at all! That’s why most TVs have an array of thin, high quality lights built into the sides or back of the TV panel.
A few years ago flat panel TVs used skinny fluorescent tubes, not that different from typical office ceiling lights. Today, however, nearly all TVs use LED (light-emitting diode) lights. They’re brighter, more energy efficient, they don’t get as hot, and the quality of light is much better.
You can appreciate LED lighting even when the TV is off. That’s because LEDs are extremely small compared to a bulb, which has allowed TVs to get razor thin—sometimes thinner than a pencil. So why isn’t every TV that thin? And why are the really premium TVs sometimes even a little thicker?
Well, as any engineer worth their salt will tell you, there are always trade-offs. So let’s dig into how these TVs are actually put together.
The simple difference
As the name suggests, edge-lit TVs are lit from the edge. LEDs are placed on the perimeter of the television panel (usually the top and bottom). Edge-lit TVs are the thinnest LED TVs you can find, which is a big plus when it comes to looks.
Rather than just lining the perimeter, full array backlit TVs have a complete grid of LED panels behind the screen. That means a 55-inch screen TV has a matching 55 inches of high quality LED lights.
What it means for picture quality
Imagine you’re watching a scene in a movie. The scene takes places in a deep, dark cave. Both kinds of TVs would lower the brightness of the LED lights to make sure that cave looks inky black.
But suddenly, our hero of the movie enters carrying a torch that lights up the center of the screen, while the darkness of the cave presses in on her from all sides.
The TV now has to make a choice about how to balance these two opposing needs: bright in the center, dark around the edges.
A full array backlit TV has an advantage. It can turn up the brightness on just the LED lights directly behind that part of the screen where the torch is. This is called local dimming.
Many edge-lit TVs also have local dimming. It’s just not quite as exact in its localization, because the LED lights live on the edges of the panel. The result is that most of the cave will still appear inky black, but the black areas close to the torch might appear less, well, inky.
How does this impact wallet?
It should come as no surprise that film buffs and gear heads love full array backlit TVs. They make for a tremendous theatrical experience.
The trade-off on full array is usually price and aesthetics. All those LED backlights take up more space in the TV’s body, so it’s going to be thicker. Also, more lights mean more internal parts, and each segment of lights has to be carefully engineered for maximum performance. That’s all reflected in the price tag.
Edge-lit TVs have a simpler design, so they tend to be more affordable than backlit TVs.
No bad choices
Because LED lighting is, in itself, pretty amazing, it’s easy to see why TV makers have played around with different designs to take advantage of all the benefits. Backlit TVs aren’t inherently a better choice than edge-lit TVs, or vice versa.
While it’s true that the picture quality in backlit TVs is superior, the affordability and looks of edge-lit TVs make for a pretty strong argument. Not to mention that this year’s crop of edge-lit TVs offer remarkable performance in their own right.
There are no bad choices. We recommend swinging by your local electronics store for a test drive and seeing for yourself.
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