Today the U.S. Patent Office published a patent application of Apple's that relates to future foldable devices from Apple. A device hinge allows the device to be flexed about a bend axis. Apple notes that foldable devices could include an iPhone, iPad, MacBook, an iMac and others.

Electronic Devices With Flexible Displays

According to Apple, an electronic device may have a hinge that allows the device to be flexed about a bend axis. A display may span the bend axis. The device may have a stainless steel and/or carbon fiber reinforced polymer layer with slots. The slots may overlap the bend axis. The slots may have at least one property that varies in a non-linear manner as a function of position on the layer. The device may include an adhesive layer with a cutout that overlaps the slots.

An interface that defines the cutout may have a plurality of recesses with varying depths. A flexible printed circuit may be attached to an edge of the display panel. The display cover layer may overlap a bonding region between the flexible printed circuit and the edge of the display panel. A UV-curable gap filler may be interposed between the flexible printed circuit and the display cover layer.

Apple's patent FIG. 19 below is a top view of an illustrative layer #62 with interlocking features between different sublayers. As shown, carbon fiber reinforced polymer sublayer #84 in display portion #62B is interposed between polymer portions #92 from display portions #62A and #62C.

On each side of the carbon fiber reinforced polymer sublayer, interlocking features #98 are included that include one or more protrusions and recesses with sloped sides that are non-parallel and non-orthogonal to the X-axis and Y-axis.

In the arrangement of FIG. 19, each interlocking feature includes a trapezoidal protrusion that extends away from the display portion #62B. Each trapezoidal protrusion has a corresponding trapezoidal recess (e.g., in the non-central edge of the trapezoidal protrusion).  The footprint of the interlocking features helps ensure a secure attachment between sublayers #84 and #92. 

Apple's patent FIG. 22 above is a top view showing how one or more strain gauges may be positioned on display #14. The strain gauge(s) may be positioned in flexible portion #14B of the display that is bent during folding and unfolding of the display. This positioning enables the strain gauge(s) to precisely detect the angle of display portion #14A relative to display portion #14C (as the angle may be a function of the strain detected by the strain gauge).

One strain gauge may be sufficient to measure the strain on the display and detect folding and unfolding of the display. However, as shown in FIG. 22 an additional strain gauge may be included to improve precision and provide redundancy in case one of the strain gauges malfunctions.

One or more sensors for gathering data on device position and motion may also be included in the display As shown in FIG. 22, a first motion sensor #508 may be positioned on display portion #14A and a second motion sensor may be positioned on display portion #14C.

The motion sensors may be inertial measurement units that include accelerometers, compasses, and/or gyroscopes, as one example.

Apple's patent FIG. 31 above is a top view of an illustrative Kirigami layer with slots having starting positions that vary according to multiple sinusoidal trendlines.

Side Note: Kirigami is generally used as a technique to make (meta)materials and (meta)structures with extraordinary properties such as negative Poisson’s ratio. In doing so, a given material/structure is transformed into a metamaterial/megastructures with properties which do not exist in the initial material/structure.

FIG. 26 is a flowchart of an illustrative method for outputting a notification based on temperature and a speed associated with bending the display

For full details, review Apple's patent application 20250028365.

A Few of Apple's Inventors

• Sijun Niu: Display Mechanical Engineer
• Wei Lv:  Hardware Design Manager
• Tyler Kakuda: Mechanical Engineer (Macs)
• Ying Wang: Sr. Deep Learning Compiler Engineer