Curved OLED HDTV screens are a bad idea (for now)

Both Samsung and LG, two of the biggest players in the burgeoning world of organic light-emitting diode televisions, have announced (or depending on where you live, are selling) curved OLED screens to go along with traditional "flat" OLED screens.

Curved screens have been used in theaters for decades, and more recently in some high-end home theaters, too. In a TV though, it's nothing more than a gimmick.

Here's why.

Let me say up front that I am a huge fan of OLED. So much so that it pains me to write this article. OLED promises better picture quality than plasma, better energy efficiency than LED LCD, while being both thinner and lighter. You can sort of buy an LG model right now, and Samsung's version seems perpetually on the horizon. We saw prototypes of 4K OLED TVs from Sony and Panasonic (they've teamed up), but nothing else so far. The issue is, and long has been, making them cheap enough to manufacture.

Curved screens have been found in many theaters, the most famous probably being the Cinerama Dome in Hollywood. It's not a new idea, but the benefits still hold true today...in certain circumstances. With really large screens, one of the biggest advantages is being able to "focus" more light toward the audience. Another is reducing optical distortions when using certain projection lenses. There's also a potential "naturalness" to an image that has every part equidistant to your eyeballs. But perhaps the most notable benefit is the ability to fill a massive percentage of a viewer's field of view. Sitting in the right seat, you could have the image practically wrapped around you.

This is how Samsung describes the benefits of a curved screen: "the curved panel allows the distance between the user and TV screen to be the same from almost any angle." And LG's take: "With a gentle inward flex, the entire screen surface is equidistant from the viewer's eyes, removing the problem of screen-edge visual distortion and detail loss." So by their own definitions, one of the main reasons to have a curved screen is so every part is the same distance from the viewer's eye.

Radius, radii, radiuses
The problem is not with the idea of curved screens, but a curved screen TV. To get the benefit of a wraparound image, or even the benefit of a more natural image that has every part equidistant from your eye, you need to be sitting in a pretty specific place. With a theater screen, that place is an area big enough in which a lot of people can sit. Sure, people off to the sides aren't getting the best effect (if any), but the folks in the middle are. With a smaller curved screen, that sweet spot is a lot smaller.

Small TVs don't have a very large sweet spot to begin with. (I'm counting 55-inch TVs as small in this context, as they are small compared with theater screens.) Let's take the curved aspect out for a moment. What's the ideal seating area for a 55-inch, 1080p TV? That's actually pretty easy. You should be sitting close enough so that you're able to see all the resolution. Not so close that you can see individual pixels, but not so far that the TV could be 720p and it wouldn't look any different. You also want it to fill your field of view enough so that it's not like looking at a postage stamp from across the room.

I covered this from the other side in "How big a TV should I buy?" and we can use similar math here. THX recommends the TV fill 40 degrees of your field of view. So for a 55-inch TV, it's recommending you sit 66 inches away. This is also about where people with 20/20 vision are seeing all the resolution possible with 1080p. SMPTE recommends 30 degrees, so it's saying you should be 88 inches away.

So ideally, a curved OLED screen should have a curve whose radius is somewhere between 66 and 88 inches. Since most people still sit about 108 inches from their TVs, we could even accept this as an outside number.

Thankfully, Dennis Burger of HomeTechTell did some math and research on the curved part already. He figured that at a distance of 90 inches (well within our range), the TV would need a curve of about 3 inches between the center and the edges. The LG is not nearly this deep. According to LG, the OLED's curve is 5 degrees, not the 7.5 needed for a 90-inch viewing distance. How different is that? Well, the LG's "sweet spot," based on its curve, is 134 inches away. Over 11 feet. Not only is this farther than most people sit from their TV, but it also means it might as well be 720p. In other words, in order to get every part of the screen equidistant from your eye, LG's stated goal, you have to be sitting so far away that the screen will look tiny.

But this is all getting into the weeds. Even if a new curved OLED screen comes out, it effectively requires the owner to sit at a rather precise distance from the screen. Too close or too far, and the curve loses its major benefits. And let's not forget, this is for one viewer. With several people on the couch, all the claimed benefits are lost.

Bottom line
Look, the fact that a "flat"-screen TV can be curved at all is pretty amazing. But since OLED is barely off the ground (arguably, not off the ground at all), it's disappointing to see finite resources going into something of little value beyond "hey, neato" which, also arguably, OLED inherently has already.

However, this won't always be the case (we hope). The beauty of OLED is that, in theory, it's scalable in size and resolution. So projection-screen-size, or even wall-size OLED screens are theoretically possible. In that case, a curved screen could be pretty awesome.

And while we're dealing with this far off future, how about a flat, wall-size OLED screen that, at the touch of a button, curves in at the edges for movies? Flexible OLED screens. That's a thing, too. Hurry up future times.

Got a question for Geoff? First, check out all the other articles he's written on topics like HDMI cables, LED LCD vs. plasma, Active vs Passive 3D, and more. Still have a question? Send him an e-mail! He won't tell you what TV to buy, but he might use your letter in a future article. You can also send him a message on Twitter: @TechWriterGeoff.