Apple Inc.
Sensing force and press location in absence of touch information

Abstract:

Disclosed are electronic devices and methods of their operation that use force sensors to detect user applied forces on an input surface and determine their locations on the input surface, using only force sensors. The locations may be determined using weighted averages of the positions of the force sensors and their values. The methods may compare dynamically updated baseline force values to received force sensor values to distinguish user applied forces from changes in the force sensor values caused other sources. After detection of a user applied force, the baseline force values are frozen, and the force sensor values used to find the location on the input surface where the user applied the force. The electronic device can operate according to a state space model, with a first state in which there is no user applied force, and a second state in which there is user applied force.