By Aldo Cugnini
Earlier this year, we saw the introduction of curved displays from a growing set of manufacturers — Sony, Panasonic, LG, Samsung, Haier, Konka, to name a few — and are motivated to explore how useful (or desirable) such displays can be. The answer is somewhat complicated, involving as it usually does in this area, both physics and perception.
Does a curved screen provide a greater sense of reality for video content? After all, the ultimate goal for any large-video display technology is to offer an image rendition that makes the viewer forget they are looking at a display. So, for large screens, a curved display would seem to have certain technical advantages over a flat one. First, there is the issue of image distortion, as well as illumination characteristics — brightness,contrast, color fidelity, etc. — across the screen.
Projector manufacturers have known about these factors for a long time, and often provide curved projection screens to improve performance. However, using a curved screen in a home environment is problematic — the curve works best for viewers sitting at a sweet spot near the center of the radius of curvature, and that means that ideal group viewing becomes awkward or even impossible.
Curved Display Width Advantage
Nonetheless, there is an improvement in screen real estate that can benefit: a curved screen will provide a wider field of view (FOV) than a flat screen of the same width. The advantage is about 5 percent for a FOV of 45°, growing to about 25 percent for a FOV of 90°. The larger FOV, however, would imply either a very large screen in a TV-viewing situation, or a more practical screen used as either a computer monitor or virtual-reality/gaming display. Of course, the improvement would hardly offset the manufacturer’s cost premium, if one considers the size to offer a “smaller” display for the same FOV.
A curved display can have other advantages for virtual reality as well. A 2004 experimental study conducted by the Max Planck Institute for Biological Cybernetics found that large curved screens seem to be more suitable than flat screens to simulate what they call “rotational ego-motion,” i.e., when the scene attempts to replicate the feeling of the viewer rotating in place. But this is a rather limited effect, when considering all the different motions one would want (or need) to simulate.
For mobile phones and wearable devices, however, the advantages are more tangible. The Samsung Galaxy Round smartphone, for instance, has a curved screen. Although the curvature is very subtle, just 0.10 inches away from flat, the small curvature is said to significantly reduce interference from reflected ambient light, a characteristic borne out by DisplayMate in a shoot-out last year. And Samsung recently released the “first curved wearable device with a Super AMOLED display,” the Gear Fit. For arm-strapped phones and fitness devices, such a form factor could provide a useful improvement over flat displays.
Of course, we can’t ignore the other perceptual/psychological benefits of a curved display — the “cool factor” — but those are harder to define, and carry the risk of lowering the technology to a fad. DisplaySearch rendered such a verdict earlier this year. But visual innovation is often the hallmark that differentiates wide swaths of products: consider the broad appeal of the clean lines of so many Apple products, and you get the point. In fact, we haven’t yet taken “curved” to all of its possibilities: could the “reverse curved” screen rumored to be in the works for the iPhone 6 (and envisioned by one designer in a video) become reality? Why not?