Today the U.S. Patent Office published a patent application of Apple's that relates to iPhones and iPads that employ a transparent cover glass disposed over a display screen. The cover glass can have one or more layers that comprise silicon dioxide, silicon nitride, or silicon oxynitride, among other materials that are stronger than glass.

Burnish-Resistant Glass Laminate with Buried Interference Layer

Electronic devices, like an iPhone or iPad often use a cover glass to protect its touch-sensitive display from damage. The cover glass may have a relatively soft top layer that forms an anti-reflective coating to improve the appearance and usability of the electronic device in lighted areas. As the cover glass forms an exterior portion of the enclosure of the electronic device it is subject to mechanical damage, scratching and/or burnishing.

In particular, when the outermost layer of the cover glass includes a relatively thin layer of silicon dioxide, the relatively soft silicon dioxide layer may easily become burnished, where the outermost atomic layers are worn down via repeated rubbing on an adjacent surface.

The present technology can overcome these issues by forming an exterior hard-coat layer to improve the scratch and burnish resistance of the cover glass, and forming a buried interference layer below the hard coat layer to reduce the reflectance of the cover glass.

In one example a cover glass includes a burnish-resistant exterior hard coating made from silicon oxynitride. An interference layer is formed below the exterior coating and can include a layer of silicon oxynitride, a layer of silicon dioxide and another layer of silicon oxynitride to interact with the exterior layer to improve the reflectance of the cover glass. The optical constants and/or thicknesses of the interference layers can be determined based on the optical constant and/or thickness of the exterior coating to reduce the reflectance of the cover glass (e.g., via engineered destructive and/or constructive interference).

In some embodiments a gradient layer can be first deposited on the glass substrate and a relatively thick intermediate hard-coat layer can be deposited on the gradient layer. The gradient layer can gradually transition from a composition of the glass at the glass substrate to a composition of the intermediate hard-coat layer (e.g., silicon oxynitride) at the intermediate hard-coat layer. The interference layer can then be deposited on the intermediate hard-coat layer and the exterior hard-coat layer can be finally deposited. The gradient layer can improve the reliability of the interface between the intermediate hard-coat layer and the glass layer while the intermediate hard-coat layer can be relatively thick and protect against deep scratches in the cover glass. The buried interference layer can improve the reflectance of the cover glass, for example, as compared to a cover glass without the interference layer.

Apple notes that this process may also apply to future Apple Watch displays.

Considering that Apple's patent was only filed in September 2024, this is highly unlikely to be the cover glass formula used for the new iPhone 16 or 16e. Apple is always trying to improve specifications from one iPhone generation to the next, and so this is likely the next generation cover glass being described.

  Apple's listed Inventors

•  Matt Rogers: Director of Glass, Ceramics, and Coatings Team
• Tyler Roschuk: Product Design Materials Engineer
• Lijie Bao: (No profile found)