Articulated hinge structures for foldable iPhone detailed in new research

Apple is continuing to develop non-traditional display technology that can fold out and expand along hinge articulation points, likely for a future foldable iPhone.

The company's work on foldable display technology is no secret due to the slew of related patent applications it has filed. Some of those patents detail scroll-like or slidable displays that expand.

And in a patent application published Dec. 3 and titled "Electronic devices having folding expandable displays," Apple continues that research with much more detail about potential hinge structures.

The multi-link hinge structure described in the patent. Credit: Apple

The first figure in the patent, which was first filed in February 2020, details a foldable device bent at a right angle. Notably, the figure shows a new multi-link hinge structure with more than just one articulation joint.

This is only one such potential hinge that Apple is researching. The patent text indicates that hinge structures could include "gear teeth, belts, and/or other movement synchronization structures" and may also sport "members that move relative to each other during bending."

Those moving members may compromise bars and links with opposing curved bearing surfaces, including stop surfaces that "prevent excessive rotation of the bars and links with respect to each other." These links could rotate around a pivot point that lies within a display without the actual hinge structure "living within the thickness of the display."

The patent also calls back to other expandable or slide-out displays, noting that a device with "housing structures that support folding motions, sliding motions, scrolling motions, and/or other behavior" could provide more screen real estate for users in a compact size.

Additionally, the patent runs through some ways that a hinge structure could prevent undue display stress during folding and unfolding, including specific hinge types, stress minimization components, stop surfaces, and friction to control the amount of force applied to the hinge.

Apple doesn't restrict the display technology to the iPhone, either. It notes in the patent that the foldable or expandable device could be applied to a slew of different device types, including wristbands, pedants, laptops, glasses, goggles, embedded kiosk systems, or devices within vehicles. The depiction of the device as a smartphone is just an example, the patent adds.

A good portion of the patent details the kinds of materials such a device could be crafted from; the kind of electronic circuitry that would power it; and the types of sensors, buttons, and other components.

The patent lists Owen D. Hale; Tatsuya Sano; Chang-Chia Huang; Yasmin F. Afsar; Hoon Sik Kim; and Michael B. Wittenberg. Of them, Kim has worked on different expandable display technologies for Apple, while Wittenberg was named in an Apple Watch band patent and a force-sensitive Touch ID patent.

Apple files numerous patents on a weekly basis, so they are not a reliable indicator of the company's imminent plans. More than that, they don't provide any timeline for when such technology could reach the market.