As Apple continues to work on a foldable iPhone, a newly published patent application spotlights geared hinges that would permit the user to fold the device both ways.
You'd be able to open it inwards, like a book, or outwards, so that one screen wraps around the back of the other, with geared hinges strengthening the whole thing. Apple's patent application for "Folding Electronic Devices With Geared Hinges" attempts to address concerns that portability may come at the expense of usable screen space.
Portability vs. Screen Space
"If care is not taken, a display may not offer sufficient screen real estate to display information of interest to a user," reads the description in Apple's filing with the USPTO. "At the same time, it can be difficult to enlarge the size of electronic devices too much to accommodate larger displays, because this can make devices bulky."
The included drawings illustrate a geared hinge mechanism moving from folded to unfolded. The hinge may use "toothed members such as gears and a rack member" (the surface that holds the screen which the user sees) which may feature a surface "with curved portions".
A Foldable iPhone With Geared Hinges
"The hinge may include gears that are fixedly attached to the first and second housing portions and that engage the rotating gears," reads the patent application. "Linkage members may hold together the rotating gears, fixed gears, and the rack member."
Those articulated hinge structures were outlined in many other Apple patents, strongly suggesting that a foldable iPhone may have been in development for quite some time now. In fact, Apple may be close to finalizing the device with the rumor-mill claiming recently that two different folding iPhone prototypes recently passed quality control checks.