Apple began exploring devices that would offer an expandable display using a scrollable/rollable display back in 2014. Since then we've covered several other patents over the years (01, 02 and 03 and more). Today the US Patent & Trademark Office published another patent application from Apple that relates to the possible use of a rollable/scrollable display within a device. Apple lists  an iPhone, iPad, television (see a video example below), desktop display, vehicle dashboard (see a video example below) and more as devices that may use such a display in the future.  

Apple's invention covers an electronic device having a rollable display. The display may be moved between an unrolled state in which the display is unrolled for viewing and a rolled state in which a rollable portion of the display is rolled up for storage. In the unrolled state, the display may be planar. In the rolled state, the rollable portion bends about an axis as it is rolled onto a roller for storage.

The display may have a display panel with a pixel array that produces images and a transparent protective layer that overlaps the pixel array. The transparent protective layer may contain a layer of glass. The glass layer may be locally thinned in the rollable portion to facilitate bending.

During use of the device, the outwardly facing surface of the transparent protective layer may be exposed to objects that can create scratches, whereas the inwardly facing surface of the transparent protective layer may be protected and thereby have fewer surface irregularities.

To help prevent cracking in the glass layer, The display may be configured roll so that its outwardly facing surface receives compressive stress. Compressive stress in the outwardly facing glass surface may help prevent any scratches in the outwardly facing display from causing cracking or other damage to the display when the display is bent during rolling operations.

Apple's patent FIGS. 5 and 7 are cross-sectional side views of illustrative displays with rolled portions. More specifically, FIG. 7 is a cross-sectional side view of an illustrative electronic device in which an outwardly facing surface of a display has a first area that receives compressive stress when rolled while a second area receives tensile stress.

According to Apple, display #14 may have an array of pixels configured to display images for a user. The pixels may be formed as part of a display panel that is bendable. This allows the device to be bent about a bend axis. For example, a flexible (bendable) display in a device may be partly or completely rolled up so that the device may be placed in a compact shape for storage and may be rolled out when it is desired to view images on the display.

Displays with rollable structures may sometimes be referred to herein as rollable displays, scrollable displays, flexible displays, or bendable displays. A rollable display may be completely rollable (e.g., flexible over its entire area) or may be partly rollable (e.g., one or more edge portions of a display may be provided with sufficient flexibility to be rolled whereas one or more other portions of the display may be less flexible and/or may be fixed in a planar state).

Apple describes a protective display layer that may include clear polymer, clear glass, and/or other transparent structures that allow images to be viewed while providing support (e.g., rigidity) and protection (e.g., protection from scratches and other damage) for the display panel. As an example, a layer of glass that is attached to the outer (front-facing) surface of the panel that may be used to prevent the display panel from deforming and becoming damaged when a user's finger, computer stylus, or other external object contacts the front side of the display.  

For more details, review Apple's patent application number 20230221766. Apple's latest patent on this subject was filed in November 2022 and published today.