On September 12, 2013, the US Patent & Trademark Office published a patent application from Apple that reveals their intention to add a sapphire laminate to future iDevices like the iPhone and iWatch to provide a stronger glass that is ultimately scratch resistant. It was revealed earlier this week that Apple's new iPhone 5S Home Button is made from laser-cut sapphire crystal. Apple's patent application describes their method of fusing a sapphire laminate sheet to a device's cover glass.
Apple's Patent Background
Corundum is a crystalline form of aluminum oxide and is found in various different colors, all of which are generally commonly referred to as sapphire except for red corundum which is commonly known as ruby and pinkish-orange corundum which is known as padparadscha.
Transparent forms of corundum are considered precious stones or gems. Generally, corundum is extraordinarily hard with pure corundum defined to have 9.0 Mohs and, as such, is capable of scratching nearly all other minerals. For the present purposes, the terms "corundum" and "sapphire" may be used interchangeably to refer generally to the crystalline form of aluminum oxide.
As may be appreciated, due to certain characteristics of corundum, including its hardness and transparent characteristics, among others, it may be useful in a variety of different applications. However, the same characteristics that are beneficial for particular applications commonly increase both the cost and difficulty in processing and preparing the sapphire for those applications. As such, beyond costs associated with it being a precious stone, the costs of preparing the corundum for particular uses is often prohibitive. For example, the sapphire's hardness makes cutting and polishing the material both difficult and time consuming when using conventional processing techniques. Further, conventional processing tools such as cutters experience relatively rapid wear when used on corundum.
Apple's Invents a Fusion Process for Adding a Sapphire Laminate to Device Cover Glass
Apple's invention relates to various sapphire structure and laminate structures. One embodiment as noted in our graphic below as FIG. 8, may take the form of a sapphire structure having a first sapphire sheet with a first sapphire plane type forming the major surface and a second sapphire sheet having a second different sapphire plane type forming the major surface. The first and second sapphire sheets are fused together to form the sapphire. Apple notes that the glass structure is less than or approximately equal to 1 mm thick.
Apple's new method also includes lapping and polishing a second side of the sapphire sheet and chemically strengthening the glass sheet.
The use of a sapphire outer surface with a glass inner surface for the display may be used in future iDevices where the two sapphire surfaces are laminated together with the glass providing support for the display and the sapphire providing scratch resistance and durability advantages.
Apple currently uses a sapphire finish on their iSight Cameras for iDevices and for the new iPhone 5S Home Button. Apple further notes that the use of a sapphire laminate may be used in future products including Macs, a watch or other mobile devices.
Apple credits Christopher Prest, Dale Memering, David Pakula, Richard Dinh and Vincent Yan as the inventors of this patent application which was originally filed in Q1 2013. To review Apple's new fusion process for producing a laminate sheet for use in glass structures, see Apple's patent application 20130236699.
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