Apple Invents Crack Resistant Glass Solutions for Portables
While Donald LeBuhn was filing a class action lawsuit against Apple back in January of this year, accusing the company of misleading customers as to the strength of the glass used in its iPhone 4, Apple was already well into inventing new crack resistant glass solutions for portables like the iPhone. The new solution involves a tunable shock mount that sits between the glass and the body of the device. The specialized mount could be instantly inflated if the device senses a drop event determined by its internal accelerometer. Apple's patent describes using exotic materials that could protect the glass from shattering. As a side bonus, Apple is also considering a solution that could provide portable devices with a new water damage prevention seal. Two Updates have been added to this report
The Problem: Portables are Susceptible to Cracked Glass
Conventionally, small form factor devices, such as handheld electronic devices, have a display arrangement that includes various layers. The various layers usually include at least a display technology layer, and may additionally include a sensing arrangement and/or a cover window disposed over the display technology layer.
The cover window, or glass cover, for a small form factor device could be made of plastic or glass. Plastic is durable but susceptible to being scratched. Glass is scratch resistant, but brittle. The rigid nature of glass makes it susceptible to cracking if subjected to significant forces. For example, users of handheld electronic devices occasionally drop their device onto a floor or other hard surface, and the resulting impact forces could cause the glass to crack.
In general, the thicker the glass, the stronger it is. Unfortunately, however, with low profile handheld devices, the glass cover is often relatively thin, and tends to be susceptible to damage when the small form factor device is stressed as, for example, when dropped onto a floor. Here, the glass cover may crack or break as a result of being dropped onto the floor. As handheld electronic devices become thinner, the glass cover sheets used on the handheld electronic devices typically also becomes thinner and, thus, more susceptible to damage.
Thus, there is a continuing need for improved approaches for glass cover arrangements for electronic devices that are configured to avoid unnecessary damage.
Apple's Proposed Solution: Integrating a Shock Mount into Devices
Apple's invention patent covers apparatus, systems and methods for shock mounting a cover glass for an electronic device. In one embodiment, a method for assembling an electronic device could include at least providing a housing for an electronic device, and compliantly attaching a cover glass to at least a portion of one surface of the housing, whereby cover glass serves as an outer surface for the at least a portion of one surface of the housing.
In one embodiment, a consumer electronic device could include a cover glass, and a shock mount disposed between the cover glass and a remaining mass of the electronic device. The shock mount is configured to isolate the cover glass from the remaining mass of the electronic device.
The apparatus, systems and methods for shock mounting glass are well suited for cover glasses or displays (e.g., LCD displays) assembled in small form factor electronic devices such as the iPhone, iPod Touch or remote controllers. Yet it the invention also may apply to the iMac, Cinema Display, the iPad, MacBook and televisions.
Sensing Drop Events & Implementing a Mechanically Actuated Retractable
In another embodiment, a consumer electronic device could include a housing, a cover glass provided adjacent to at least one surface of the housing, and electrical components provided at least partially internal to the housing. The electrical components include at least a controller, a memory, a display, a sensor, and an actuator. At least the controller and the sensor are used to sense a drop event. The actuator could be coupled with the cover glass for withdrawing the cover glass at least partially into the housing in response to sensing the drop event, thereby protecting for the cover glass. Elsewhere in the patent Apple describes this as a "mechanically actuated retractable."
Apple states that another advantage to their invention is that electronics disposed within a housing of a device could be protected from water damage by using a water seal.
The Tunable Shock Mount
Notably in patent FIG. 1A, the electronic device has a cover glass (104) with a tunable shock mount (105) which could be disposed between the cover glass and the housing (102).
Considering that the thickness of the cover glass could be rather thin (i.e., less than a few millimeters), the cover glass if not carefully arranged could be susceptible to cracking or breaking in an accidental drop event. Therefore the cover glass could be suitably arranged with the tunable shock mount noted above which could be tuned so as to limit susceptibility to damage.
The tunable shock mount may be disposed between the cover glass and the main body of the device. As particularly shown above in sequential end views of the electronic device before a shock event in FIG. 1B, and after a shock event in FIG. 1C, the tunable shock mount could provide compression and dampening, so as to isolate the cover glass from the remaining mass of the electronic device.
The cover glass has a substantially planar surface, and the tunable shock mount is arranged so as to provide compression and dampening along a direction normal to the planar surface of the cover glass (for illustrative purposes in FIG. 1C, the direction normal to the planar surface is shown by a notional arrow with the legend "N").
In response to such shock events, the cover glass could resonate. The cover glass could have a corresponding resonant frequency. Similarly, the remaining mass of the electronic device could have a corresponding resonant frequency. The tunable shock mount could be tuned to have a resonant frequency that is substantially lower than the resonant frequencies of the cover glass and the remaining mass of the electronic device. Additionally, the tunable shock mount could be tuned so as to be substantially critically damped.
Strengthening the Glass
One aspect of this invention has already been put into place on iOS devices. The invention describes using alumino silicate glass which is commercially known as Gorilla Glass. But other glass materials that could be used in the future include sodalime and borosilicate that are known to make the glass resistant to thermal shock.
Moreover, the cover glass pieces can be chemically treated for further strengthening. One suitable chemical treatment is to place the cover glass pieces in a chemical bath containing potassium (e.g., KNO.sub.3) for a period of time (e.g., several hours) at an elevated temperature. The chemical treatment could desirably result in higher compression stresses at the surface of the cover glass pieces. The surface of the cover glass pieces includes the edges of the cover glass pieces. The higher compression stresses may be the result of K+ ions effectively replacing some Na+ ions at or near the surface of the cover glass.
Update # 1 Nov 18, 2011 4:44 PM MST: I've heard some people denigrating Apple by saying that Apple's use of old technology like Gorilla Glass for the iPod is a rip off and other such nonsense. The fact is, that on page 472 of Isaacson's biography of Steve Jobs pertaining to Gorilla Glass, we read Corning's CEO Wendell Weeks state that "we produced a glass that had never been made." Furthermore he stated "We put our best scientists and engineers on it, and we just made it work." All in context with the iPhone. The fomula of the original Gorilla glass wasn't what ended up in the iPhone. So even though Corning has kept the "Gorilla Glass" branding, we now know that the iPhone ended up with their all new formula which revived the product that Corning had no original market for.
The Material Makeup of the Tunable Shock Mount
A material of the tunable shock mount (205) may include a polymer, a foam, a gel, a viscoelastic material, a shape memory material, an exothermic material, an optically transparent material, a silicone rubber material or other suitable material. Depending in part upon the material or materials selected for the tunable shock mount, and upon parameters such as compressive stiffness and/or dampening of such material or materials, dimensions of the tunable shock mount such as a width dimension "w" and/or a thickness dimension "t" shown in cross-sectional views in FIGS. 2B and 2C may be selected so as to provide tuning.
Apple's reference to "shape memory material" may very well relate to another patent of theirs that surfaced back in June 2010. Our patent report on this subject matter described likeminded properties under the header "Shape Shifter Nodes and Materials."
A Tunable Shock Mount with Micro Inflatable Bladder
Apple's patent FIG. 5 shows a housing and a cover glass in cross sectional view having a tunable shock mount 505 disposed there between. The tunable shock mount could comprise of an inflatable bladder 506 filled with a fluid 507. Tuning could be done in various ways such as by selection of materials for the bladder and fluid, and by varying an amount of inflation. Hmm, think of it as a form of air-bag for portable devices.
Apple's patent applicationwas originally filed in Q2 2010. One of the inventors named in the patent is Stephen Lynch who has worked on such projects as the iPod touch and wireless inductive charging.
Update #2 November 28, 2011: Apple gained a new round of design patents from China today. Of interest is one design that illustrates a raised rim. This might, and I stress might, be illustrating another protective measure being considered by Apple to protect the iPhone's Glass face. Time will tell.
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First and foremost all idevices don't use gorilla glass. Secondly, Apple will not let Corning state that gorilla glass is on the devices like they can with Samsung.
Another thing is this design simply will not work or help unless the glass edges are more protected. Weakest point of the glass is the edge and you'll see most breaks occur there.
Posted by: John | November 22, 2011 at 06:02 AM
Why not just use tempered glass and keep it simple?
Posted by: AVD | November 21, 2011 at 11:41 PM
I couldn't disagree with you more Bret. If you look at figs 1b and 1c you get that it's basically hidden until it's dropped and even then it only opens a tiny bit. It's a real effort to cushion the glass. They're being sued now and it's a bigger motivator to try and find a solution. Whether this is the only solution Apple is working on is a different matter.
Posted by: Maureen | November 18, 2011 at 07:47 AM
Seems a way overcomplicated and inelegant solution.
Posted by: bret | November 18, 2011 at 07:41 AM
Gorilla Glass, of course, is a trademark of Corning Incorporated... and is used in/on a large percentage of screens in today's portable devices. Never touted as "unbreakable", Gorilla Glass is simply many times stronger and much less scratch resistant than sodalime or borosilicate glass.
Corning would be smart to work with Apple on this project. Being able to market their glass screens with the airbag-like features presented here would benefit them both.
Posted by: the Ryan | November 17, 2011 at 06:34 PM
This is a pretty interesting and impressive use of the accelerometer.
Posted by: Gorilla Glass | November 17, 2011 at 06:05 PM