Last week we posted a report titled "Apple Reveals an Oleophobic Coating on Sapphire Process for iDevices that may Incorporate Liquid-Metal." The week prior we reported that Apple revealed laser cutting techniques for processing sapphire . The wave of sapphire related patents continues for the third straight week with one titled "Continuous Sapphire Growth." Apple's patent application relates to sapphire growth and, more particularly, to systems and methods for continuous sapphire growth.

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.

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 conventional processing techniques are implemented. Further, conventional processing tools such as cutters experience relatively rapid wear when used on corundum.

Apple's Invents Sapphire Growth Systems

Apple's invention generally relates to systems and methods for continuous sapphire growth. One embodiment may take the form of a method including feeding a base material into a crucible located within a growth chamber, heating the crucible to melt the base material and initiating crystalline growth in the melted base material to create a crystal structure. Additionally, the method includes pulling the crystal structure away from crucible and feeding the crystal structure out of the growth chamber.

Another embodiment may take the form of a system for continuous sapphire growth including a vertical growth chamber and a crucible positioned within the growth chamber.

The crucible includes a die set and is configured to hold molten alumina. The system also includes a heater configured to heat the crucible and a feeding system for continuously feeding alumina into the crucible. A pulling system is provided and configured to contact a seed crystal with molten alumina at the top of the die set and pull a crystal ribbon upwardly and out of the growth chamber.

Apple's patent FIG. 1 illustrates an example continuous crystal growth system.





Apple's patent FIG. 2 is a top-down view of a crucible of the continuous growth system of FIG. 1 showing inlets for continuous feeding of alumina.

Apple's patent FIG. 3 illustrates zoomed in view of the continuous growth system with crystal ribbons exiting a growth chamber.

Apple's patent FIG. 6 illustrates a cutting system and a testing system for the continuous crystal growth system.





Apple's patent FIG. 7 illustrates a portion of a crystal ribbon having defects.

Apple's patent FIG. 8 is an example flowchart illustrating a method for continuous sapphire growth.



Patent Credits

Apple credits Dale Memering and Scott Myers as the inventors of patent application 20140090592 which was originally filed in Q3 2012. Considering that this is a patent application, the timing of such a product to market is unknown at this time. However, in this case, Apple is likely using this invention in their new Sapphire plant in Arizona.

Some of the patent graphics presented in our report may be updated later today with finer details.

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