Apple's Patent Background

Glass parts, e.g. glass covers and/or displays, are often used in handset electronic devices. Providing a reasonable level of strength in the glass parts is crucial to reduce the likelihood of failure in the glass parts. As handheld electronic devices are often subject to being dropped or otherwise mishandled, reducing the likelihood of glass parts breaking after being dropped or mishandled is desirable. To this end glass parts are often chemically treated to increase the strength of the glass parts.

In general, slowly cooled glass such as "pot melted glass" has qualities that are desired for glass parts used in handheld devices. For example, pot melted glass has chemical strengthening properties and a thermal history that render pot melted glass particularly suitable for use in handheld electronic devices.

Most mass production processes which produce thin glass sheets and, hence, parts in relatively high volumes, require relatively rapid cooling. Pot melted processes, on the other hand, produce a slowly cooled glass that has effectively been annealed.

Mass production used to produce glass, which include fusion processes and float processes, generally don't produce glass that has the desirable thermal properties and chemical strengthening properties that may be achieved through pot melting processes. However, such mass production processes are often used, particularly when high volumes of cover glasses for handheld electronic devices are to be produced.

Therefore, what is desired is a method and apparatus which allows mass production processes to produce glass that has characteristics similar to those found in pot melted glass.

Apple's Annealing Glass Solution to Strengthen Glass

Apple's invention pertains to apparatus, systems and methods for annealing glass to improve the effect of a subsequent chemically strengthened process applied to the glass. For example, embodiment of the invention can improve the thermal properties and chemical strengthening properties of glass produces through fusion or gloat processes.

The apparatus, systems and methods for annealing and chemically strengthening glass pieces that may be assembled in relatively small form factors electronic devices such as handheld electronic handheld devices, as for example the iPhone (smartphones), iPod (media players), magic mouse, iPod touch (PDA), remote controls etc.

The apparatus, systems and methods may also be used for glass pieces such as covers or display for other relatively larger form factor electronic devices including MacBooks (portable computers), iPad (tablet computers), iMac (displays) Cinema Display (monitors) and televisions.

According to one aspect, a method for processing a glass part formed using a fusion process or a float process includes annealing the glass part and then chemically strengthening the glass part.

Annealing the glass part includes at least heating the glass part at a first temperature and cooling the glass part to a second temperature using a controlled cooling process. Chemically strengthening the glass part includes facilitating an ion exchange between ions included in the glass part and ions included in a chemical strengthening bath.

In one embodiment, the glass part is aluminosilicate glass formed using a float process. In such an embodiment, the first temperature may be between approximately 540 degrees Celsius and approximately 550 degrees Celsius.

According to another aspect, a method of processing a glass sheet formed from a fusion process or a float process includes annealing the glass sheet, machining the glass sheet to form a glass part, and chemically strengthening the glass part.

Annealing the glass sheet includes at least heating the glass sheet at a first temperature and cooling the glass sheet to a second temperature using a controlled cooling process. Machining the glass sheets includes creating a glass part from the glass sheet.

Chemically strengthening the glass part includes facilitating an ion exchange between ions included in the glass part and ions included in a chemical strengthening bath.

Apple's patent FIG. 5 noted above is a graphical representation of exemplary annealing profiles in accordance with an embodiment of the present invention.

Today Apple is using Gorilla Glass which is supposedly unbreakable as shown in the video below.

Considering that Apple works with Corning, it's a bit of a mystery as to why Apple is shown to be investigating new methods for strengthening glass for future Apple products.

Last year an Apple fan complained in a MacRumors forum that the glass on his iPhone shattered in a rather simple incident. And in 2012 Apple was sued over faulty iPhone-4 glass.

Whether the lawsuit prompted Apple to initiate new research into unbreakable glass processes or whether they have a need for stronger glass for a new project they have in mind, say an HDTV, is unknown at this time. Yet the timing of this patent is interesting considering that it comes on the heels of another European patent application discovered early last week about "Fused Glass housings for TV" and more. If anything, Apple's pace of R&D in this area is starting to get interesting.

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