Apple has patented a method of sensing the pressure underneath a user’s finger on a glass touchscreen. The feature could become a key part of the next iPhone and iPad, or could be released much later, on a future device. The patented technology uses frustrated total internal reflection of infrared light. This is a common multitouch implementation, however Apple isn’t using it to locate the location of a user’s fingers. Instead, they’re using it to infer pressure, by watching how a person’s finger would take up more space on the screen. This would work by using sensors to measure the amount of captured light under the screen, which can escape when something’s placed on the screen. The current capacitive screen would be used to tell where a user’s finger or stylus actually is. Using the two technologies together would make iOS devices capable of sensing pressure, without a screen that actually flexes. Apple could make touch screens capable of sensing pressure.
This implementation would work quite well, and would add an additional dimension to user input. It would especially be useful for artists, could be used for advanced palm rejection, and would make any stylus a pressure sensitive input source. This would certainly be a welcome feature, and one that would give iOS devices a huge competitive lead over their competition… until they copy the feature.