The first patent application related to a foldable device from Apple published today by the US Patent & Trademark Office covered the hinge mechanism of the foldable device. In Apple’s second patent application published today, Apple delves into bendable aspects of the display that could provide a bi-fold configuration and the glass-to-glass processes to allow it to be flexible.
Apple’s second folding patent application relates to techniques for forming flexible cover sheets. In particular, cover sheets can be formed to facilitate localized bending or flexing without producing unacceptable levels of internal stress.
The electronic devices may further include a flexible display layer. An exemplary electronic device includes a display layer and a cover layer coupled to the display layer and defining a foldable region, wherein the display layer and the cover layer are configured to be moved between a folded configuration and an unfolded configuration by folding the cover layer along the foldable region.
In some embodiments, the cover layer comprises a continuous layer of a ceramic material. An exterior surface of the continuous layer of ceramic material may define an exterior surface of the electronic device. Such an arrangement can present a surface resistant to shocks and/or scratches for a user. An opposite interior surface of the continuous layer of ceramic material may face the display layer.
Apple’s patent FIGS. Figures 1A and 1B below respectively illustrate a device in open and closed configuration.
Apple’s patent FIGS. 2A, 2B and 2C above respectively show in section views of a device in folded, partially unfolded and unfolded configurations.
Apple’s patent FIG. 2A is the most complex device configuration with a double fold shown which is considered in a “closed configuration”. In the fully folded or closed configuration, approximately one third of the display layer (#220) is visible along a first region (#281) of the foldable device #200. The display layer is also visible along a first collapsible region #201 of the device located along the right edge, as shown in FIG. 2A. Cover layer #210 is on the outside of the device over first region #281 and first foldable region #201. In the fully folded or closed configuration, the display layer is not visible along second region #282 and third region #283 because these regions are folded back on themselves with the display layer rotated towards the inside. Also for the second region and the third regions, the cover layer is generally protected.
Apple’s patent application details how it will treat flexible glass to be bendable using chemicals and heat treatments. For example, Apple notes that glass compositions suitable for ion exchange or field-assisted chemical strengthening include, but are not limited to, alumina silicate glass (aluminosilicate glass ), soda lime glass, borosilicate glass or glass containing lithium.
For an ion exchange process conducted primarily at temperatures below the deformation point of the glass, ions in the glass are exchanged with larger ions to create compressive stresses in an outer layer of the glass.
For example, the ion exchange process may involve the exchange of alkali metal ions, such as the exchange of sodium ions for potassium ions or the exchange of lithium ions for sodium ions. In one example, the chemical strengthening process involves exposing the glass to a medium containing the largest ion, such as by immersing the glass in a bath containing the largest ion or by spraying or coating the glass with a source of ions.
For example, a salt bath comprising the ion of interest (eg, a potassium nitrate bath) can be used for ion exchange. Appropriate temperatures for ion exchange are above room temperature and are selected based on process requirements. In embodiments, the chemical strengthening process includes one or more ion exchange steps. A multi-step ion exchange chemical strengthening process may include a step of exchanging ions in the glass for larger ions, followed by a step of exchanging some of the larger ions introduced to the glass. previous step against smaller ions.
For engineers wishing to dig deeper into the details, see the patent application United States 20220342450 A1.