A report from AppleInsider shows Apple has filed a patent application that describes a method of adding pressure sensitivity to a touchscreen using a combination of capacitive touch, infrared light and other sensing technologies without making the hardware bulky.
The patent was published by the U.S. Patent and Trademark Office on Thursday and shows the use of frustrated total internal reflection in along with other touch sensing technology that accurately determines how hard a user is pressing on screen.
In one embodiment, Apple’s system deploys one or more IR transmitters beneath the bezels of a touchscreen to emit IR light into the cover glass at a specific angle. These angles may be selected so that 100 percent of emitted light is reflected between the top and bottom surfaces of a cover glass and ambient air or a finger.
After traveling within the cover glass, the emitted IR light hits a receiver that calculates amount of total internal reflection. Depending on whether the light interfaced with ambient air or a user’s finger substantially touching the cover glass, the readings will be different.