Apple reveals in Patent that Future Foldable Devices will be Provided with Crack Resistant Display Cover Layers
On Tuesday, Apple was granted a patent for a multi-layered flip phone. On Thursday, the US Patent & Trademark Office published a patent application from Apple that related to a unique protective crack-resistant cover layer structure for future foldable devices such as an iPhone (flip phone), iPad (hybrid laptop), Macs and TV.
Hybrid Coverlay/Window Structure for Flexible Display Applications
Apple's invention is focused on correcting display cracking issues found on some foldable devices today deters many consumers from buying into whole idea of foldable smartphones at present. Apple's patent specifically relates to a new protective cover layer structure for smartphones, and more particularly for flexible displays that could fold while being crack resistant.
The patent specifically describes display modules and protective cover layer structures that may be implemented in curved, flexible, conformable and foldable display modules, and in particular with curved, flexible, conformable and foldable display panels.
Apple's patent FIG. 1 below is a schematic isometric view illustration of a protective cover layer; FIG. 2 is a schematic cross-sectional side view illustration of a bent protective cover layer.
Apple notes that typically, glass fracture initiates from the presence of micro-cracks. The hardcoat layer #104 in accordance with embodiments may fill pre-existing micro-cracks and also make it harder to initiate a crack.
Furthermore, the hardcoat layer may be engineered to have a sufficiently high hardness and tensile strength to function as an exterior protective coating for the electronic device, while being able to withstand more strain before fracture compared to the transparent support substrate #102. Thus, the hardcoat layer is sufficiently durable for high puncture and scratch resistance.
Apple's patent FIG. 4A above is a schematic top view illustration of crack propagation in a scratched transparent support substrate; FIG. 4B is a schematic top view illustration of crack propagation in a scratched transparent support substrate with hardcoat layer.
Apple's patent FIGS. 12A-12B above are schematic isometric view illustrations of an electronic device #1200 such as an iPhone. The display panel #150 and protective cover layer #100 may be curved, flexible, conformable and/or foldable. Apple's patent FIG. 12A illustrates an outward bending application, while FIG. 12B illustrates an inward bending application.
Apple listed 20 Technical Points to this Invention
- An electronic device comprising: a display panel; and a protective cover layer over the display panel, wherein the protective cover layer includes a transparent support substrate and a hardcoat layer covering an exterior facing surface of the transparent support substrate.
- … wherein the hardcoat layer further comprises a touch screen between the display panel and the protective cover.
- … wherein the hardcoat layer is characterized by a lower elastic modulus than the transparent support substrate.
- … wherein the hardcoat layer has a thickness range of 1-200 μm and the transparent support substrate has a thickness less than 150 μm.
- … wherein the hardcoat layer is on a surface of the transparent support substrate characterized by an area roughness (Ra) of 0.5 nm-10 nm, and an exterior facing surface of the hardcoat layer is characterized by a greater area roughness than the surface of the transparent support substrate on which the hardcoat layer is located.
- … wherein one or more lateral edges of the transparent support substrate are tapered.
- … wherein lateral edges further comprise of a polymer adhesion layer between the hardcoat layer and the transparent support substrate.
- … wherein the polymer adhesion layer is 1-10 μm thick.
- … wherein the transparent support substrate is formed of a material selected from the group consisting of glass and sapphire.
- The electronic device further comprises of a smudge resistant coating on an exterior facing coating of the hardcoat layer.
- The hardcoat of the electronic device has an elastic modulus range of 40 GPa-400 GPa.
- The hardcoat of the electronic device comprises a multilayer structure of materials with different elastic modulus properties.
- The electronic device's hardcoat layer provides antireflection properties.
- The adhesion layer of the electronic device is a polymer adhesion layer.
- The display panel of the electronic device is flexible, and further comprising a housing to contain the flexible display panel and the protective cover layer.
For more details, review Apple's patent application #US 20230011092 A1.
- Hoon Kim: Product Design – Special Project Group
- Nikhil Kalyankar: Lead Technologist - Optical Coatings and Films
- Paul Drzaic: Director, Display Investigations
- Yasmin Afsar: Hardware Engineer, Emerging Display Technology
- Chang-Chia Huang: Senior emerging display engineer
- Christopher Jones: Chemist/Materials Engineer
- Masato Kuwabara: Sr. Optical Film Engineer