Now, what is a foldable phone? The answer is pretty self-explanatory as you may think. Foldable phones are nothing other than phones that can be folded vertically or horizontally in half, depending on the manufacturers’ model. These phones have been introduced in the market recently and have sparked the excitement in many “tech nerds” around the world. It functions just as a regular phone does, so you can navigate on the web, make phone calls, watch videos etc., basically the same functionalities of a normal phone. Now one may ask how it is possible to have a phone that folds in half. Well, engineers were able to birth this device through a hinge mechanism that allows the phone to close up like a book or reverse the process by opening up the device to 180 degrees or even more depending on the brand of the phone (e.g. surface duo).
Foldable phones are like iPads or tablets that can fold in half but there are some exceptions like the ones engineered by Motorola which fold vertically and almost resemble a flip phone but with a touch screen body. As the shared sketches reveal (fig. 4), this phone’s patent for the clamshell design features a hinge in the middle which connects the upper and lower parts.
On the rotatable hinge, the phone will flip open from bottom to top instead of the book-like design all thanks to an intricate weave of metal teeth that allows such process to happen. Not only were the use of hinges necessary to build such device but also thin glass screens were needed in order to fold or bend the screens which would not be possible with normal glass screens. It is tough to imagine how such a brittle material like glass can be turned into a bendable flip phone, but the physics of it is remarkably simple. According to material scientists practically anything can be bent if you make it thin enough. “All the materials we know of that are very rigid can be bent to some extent,” says Schott’s Dr. Mathias Mydlak. “If you think of wood, a 2×4 cannot be bent, but if you chisel a very fine piece of it […] the same is true for glass,” he added.
A material’s chemical bonds can only be stretched to a certain extent which is known as tensile strength. But if a thinner sheet of glass is used less material is being stretched across the same space consequently stretching fewer chemical bonds. To get a glass to bend far enough for basic gadgets it must be a hundred microns thick which is around the thickness of a human hair. But thinning glass is just one of the two main ways to achieve this bending ability of the screen. The second important trick is to strengthen it against any faults such as minute scratches, tiny air bubbles, or speck of dirt during the manufacturing process. This strengthening stage is achieved by chemical baths and heat treatments to temper the glass and make it more durable. Thanks to these two main components of the device, the hinge and the thin layer of glass, its folding mechanism can gracefully open and close the phone.
Foldable phones function by a flexible display technology, which is built around OLED screens (organic light-emitting diode). Most screens use the LCD technology which are liquid crystal displays, and they are usually built around a regular glass base. With OLED screens instead, the part of the screen that emits light called pixels are built in the screen, so the LEDs are on the screen itself rather than behind the glass like on LCD displays. With OLED screens what happens is that the OLED screen technology is printed on a layer of plastic or a thin layer of glass which ends up being the screen for the phone. This is how the screen can bend or shape in various ways but there is also a side effect to using such fragile components as screen material. As it may seem, these materials are not as durable as regular glass. A little scratch on these folding screens can shatter the whole screen making the device unusable. A demonstration of how easily these special screens can be scratched or damaged is shown by a pretty notorious YouTube content creator, JerryRigEverything, who puts to test the durability of numerous devices by scratching them and so forth. So yes, these phones need extra care due to how sensitive they are yet being still a marvel of engineering.
These phones are not cheap by any means and their prices range from $1500 up to a staggering $2500+. They are not meant for everyone because these folding phones are not mature yet and come with compromises. Most folding screens are slightly worse than a normal phone because they come with a crease where the phone bends (not too noticeable but enough to catch the eye) and also as I mentioned they are not as durable as their stepbrothers. The risk of damaging your screen while using it are pretty high; even a single grain of sand could potentially destroy a folding glass screen.
The question most people ask about these phones is why do we need a folding phone? A straight answer cannot be given, and it really comes down to preference. These phones are not for everyone and as of today we do not know if these devices are going to fade away or if they are here to stay. The folding mechanism and thin complex layer of glass are such incredible technologies which open up doors for a brighter future for the phone industry. Only time will tell what is up to come.
Citations
Bohn, Dieter. “Samsung Galaxy Z Flip Review: Temper Your Expectations.” The Verge, The Verge, 21 Feb. 2020, www.theverge.com/2020/2/21/21146465/samsung-galaxy-z-flip-review-folding-glass-flip-phone-screen-camera-price.
Ismail, Adam. “Samsung Galaxy Z Fold 2 Leak Reveals Screen Size, Specs, Cameras and More.” Tom’s Guide, Tom’s Guide, 14 July 2020, www.tomsguide.com/uk/news/mother-of-all-galaxy-fold-2-leaks-reveals-screen-size-specs-cameras-and-battery.
Hollister, Sean. “Folding Glass: How, Why, and the Truth of Samsung’s Z Flip.” The Verge, The Verge, 19 Feb. 2020, www.theverge.com/2020/2/19/21142728/samsung-foldable-glass-galaxy-z-flip-explained-schott-corning.
