A new patent filing uncovered by Patently Apple illustrates Apple’s solution to prevent the glass found on a number of Apple devices from cracking when dropped.
The solution detects free fall through accelerometers found on all iOS devices, and subsequently takes action to protect the glass screen. Apple uses the same arrangement in MacBooks as well, to protect hard drives from damage arising due to drops.
The patent filing details the use of a “tunable shock mount” which would reside between the glass and the body of the device. When free fall is detected, the mount would instantly inflate, thus preventing damage to the glass. The images below illustrate the process:
The mount could be tuned to frequencies which prevent heavy vibration of the device or the glass when dropped:
In response to 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.
The mount could also comprise an inflatable bladder filled with a fluid, as shown in the image below:
In addition to absorbing shock, the patent reveals that Apple is also looking at materials like sodalime and borosilicate to further strengthen glass found on Apple devices.
Apple also describes an arrangement called “mechanically actuated retractable,” which in response to a drop, retracts the glass into the device housing, thus mitigating damage.
This arrangement in addition to protecting the glass, has two other advantages, as Apple explains:
Another advantage is that electronics disposed within a housing can be protected from water damage by using a water seal. Another advantage is a user interface can employ user movement of a cover glass for providing user input.
Till now the accelerometer could be used to detect the intensity of touch input. The arrangement above could mean an alternative, and possibly even a better way, to determine the intensity of touch.
The patent application, titled “Shock mounting cover glass in consumer electronic devices,” was filed in May last year, a month before the iPhone 4 was launched.
As with every Apple patent, this doesn’t necessarily mean you would be seeing this anytime soon in a product.
[via Patently Apple]