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Researchers Submit Patent Application, "A Mobile Electronic Device Comprising a Multilayer Sapphire Cover Plate", for Approval

July 3, 2014

By a News Reporter-Staff News Editor at Politics & Government Week -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventor Schmid, Kurt (Marblehead, MA), filed on December 9, 2013, was made available online on June 19, 2014.

No assignee for this patent application has been made.

News editors obtained the following quote from the background information supplied by the inventors: "The present invention relates to a mobile electronic device comprising a sapphire cover plate, particularly a cover plate comprising one or more layers of index matching glass on a layer of sapphire.

"There are many types of mobile electronic devices currently available which include a display window assembly that is at least partially transparent. These include, for example, handheld electronic devices such media players, mobile telephones (cell phones), personal data assistants (PDAs), pagers, tablets, and laptop computers and notebooks. The display screen assembly may include multiple component layers, such as, for example, a visual display layer such as a liquid crystal display (LCD), a touch sensitive layer for user input, and at least one outer cover layer used to protect the visual display. Each of these layers are typically laminated or bonded together.

"Many of the mobile electronic devices used today are subjected to excessive mechanical and/or chemical damage, particularly from careless handling and/or dropping, from contact of the screen with items such as keys in a user's pocket or purse, or from frequent touch screen usage. For example, the touch screen surface and interfaces of smartphones and PDAs can become damaged by abrasions that scratch and pit the physical user interface, and these imperfections can act as stress concentration sites making the screen and/or underlying components more susceptible to fracture in the event of mechanical or other shock. Additionally, oil from the use's skin or other debris can coat the surface and may further facilitate the degradation of the device. Such abrasion and chemical action can cause a reduction in the visual clarity of the underlying electronic display components, thus potentially impeding the use and enjoyment of the device and limiting its lifetime.

"Various methods and materials have been used in order to increase the durability of the display windows of mobile electronic devices. For example, polymeric coatings or layers can be applied to the touch screen surface in order to provide a barrier against degradation. However, such layers can interfere with the visual clarity of the underlying electronic display as well as interfere with the touch screen sensitivity. Furthermore, as the coating materials are often also soft, they can themselves become easily damaged, requiring periodic replacement or limiting the lifetime of the device.

"Another common approach is to use more highly chemically and scratch resistant materials as the outer surface of the display window. For example, touch sensitive screens of some mobile devices may include a layer of chemically-strengthened alkali aluminosilicate glass, with potassium ions replacing sodium ions for enhanced hardness, such as the material referred to as 'gorilla glass' available from Corning. However, even this type of glass can be scratched by many harder materials, including metal keys, sand, and pebbles, and, further, as a glass, is prone to brittle failure or shattering. Sapphire has also been suggested and used as a material for either the outer layer of the display assembly or as a separate protective sheet to be applied over the display window. However, sapphire is relatively expensive, particularly at the currently available thicknesses.

"Thus, while materials are available which can enable the display of a mobile electronic device to be relatively resistant to damage, there remains a need in the industry for materials and methods for providing improved mechanical toughness and scratch resistance without reducing transmittance."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventor's summary information for this patent application: "The present invention relates to an electronic device comprising a cover plate having at least one transparent display region. The cover plate comprises one or more glass layers having a refractive index n.sub.g and one or more sapphire layers having a refractive index n.sub.s, wherein (n.sub.s-n.sub.g) is not more than 0.05. Preferably (n.sub.s-n.sub.g) is not more than 0.03, such as not more than 0.02, and more preferably the refractive index of the glass layer is substantially the same as the refractive index of the sapphire layer. The electronic device may further comprise at least one display element having a display surface, and the cover plate can be either affixed to the display surface or removably positioned on top of the display surface as a protective layer. Preferably, the sapphire layer is the front surface of the cover plate.

"The present invention further relates to a method of preparing an electronic device comprising the steps of forming a cover plate having at least one transparent display region, wherein the cover plate comprises one or more glass layers having a refractive index n.sub.g and one or more sapphire layers having a refractive index n.sub.s; and incorporating the cover plate onto a display element of the electronic device. For this embodiment, (n.sub.s-n.sub.g) is not more than 0.05

"It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the present invention, as claimed.


"FIG. 1 and FIG. 2 are schematic views of specific embodiments of the electronic device of the present invention."

For additional information on this patent application, see: Schmid, Kurt. A Mobile Electronic Device Comprising a Multilayer Sapphire Cover Plate. Filed December 9, 2013 and posted June 19, 2014. Patent URL:

Keywords for this news article include: Patents.

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Source: Politics & Government Week

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