What it is: Foldable smartphones are the future, but which way should they bend?
Samsung recently announced their Galaxy Fold smartphone which bends vertically down the middle from top to bottom and unfolds like a book.
While interesting, the Galaxy Fold is also expensive ($1,980) which will limit it to early adopters while Samsung improves on its design. However if you look at the above two pictures, you can see there are two ways to fold a smartphone.
Samsung Galaxy Fold bends vertically while Apple has filed patents for a smartphone that bends in half or in thirds, but bends horizontally. It may not seem like much of a big deal, but from a technical point of view, it makes a huge difference.
The crease where the phone bends will exhibit repeated stress from opening and bending over and over. That means that hinge is the single most likely point of failure where failure could range from outright breaking to simply affecting the visual quality of the screen in that hinge area.
That’s why a vertical bend (like the Samsung Galaxy Fold) may look good, but creates a large stress area from top to bottom. On the other hand, a horizontal bend mimics the old style flip phones and creates a much smaller crease.
Assuming both creases fail at the same rate, the vertical fold displays the largest point of failure while the horizontal fold displays a far smaller area of failure.
The more area that could fail, the more likely it will fail. That makes the vertical crease the least reliable option from an engineering point of view.
If a phone bends in thirds, that creates two areas of potential failure, which roughly doubles its chance of failure over a phone that bends in half. Therefore a phone that bends in half like a flip phone is probably the best design to minimize stress on the foldable screen.
The hardest part about a foldable screen is making sure the creased area displays images as sharp from day one over the lifetime of the phone, which is typically 2 – 4 years. If creases become noticeable over time, then the foldable phone becomes less valuable solely due to the screen deterioration.
Foldable screens are the future, but the technology must catch up to the point where a screen can bend multiple times over years without ever affecting the visual quality of the screen. When this happens, foldable phones will become the norm. Until then, large screen non-bendable phones will continue to dominate but fade away over time.