When I read Internet articles on this patent, I thought that it's a kind of device sensing 3D spatial position of a user's finger. However, the patent reveals a different configuration. It's not a 3D spatial input device like its another patent US2008005703. The patent describes a combination of force and touch sensing.
In a user interface according to an embodiment of the invention, the processor unit 205 is capable of controlling the electronic device according to strength and direction of the resultant of the x-and y-components of the force directed to the sensor surface. Therefore, the sensor surface or a pre-determined area of the sensor surface can be used as a joystick. The force sensor equipment can be arranged to indicate also the z-component of the force directed to the sensor surface. In this case, the sensor surface or the pre-determined area of the sensor surface can be used as a three dimensional joystick (3D-joystick) for controlling the electronic device according to strength and direction of the resultant of the x-, y, and z-components of the force directed to the sensor surface.
As shown in figure below, the presented device adopts two different sensors. One is a conventional touch sensor (screen) and the other is a force sensing module. By mixing signals from those two, the host (device) can sense two dimensional finger movement with pressure. Since it can detect z directional force toward the display surface, the term "3D touch" is not a wrong understanding of this patent. However, the term 3D should be used carefully because people usually think spatial movement when they first hear the term "3D'.
The conceptually right title of the patent, I think, might be trial-axis touch sensing.
User interface (US20090256807) -