Texas Instruments Incorporated
Dual touch sensor architecture with XY-position and Z-force sensing for touch-on-surface button

Abstract:

A dual touch sensor with XY-position and Z-force sensing, such as for implementing a touch button, includes a touch sensor assembly with: (a) an XY-position sensor (such as capacitive, single ended or differential) including an XY electrode disposed at the backside of the touch surface opposite the button area to define an XY sensing area corresponding to the button area, the XY-position sensor to sense a touch within the XY sensing area, as a button-touch event; and (b) a Z-force sensor (such as inductive or capacitive) including a Z-electrode to sense touch-pressure deflection of the touch surface, including to sense a touch-pressure deflection that exceeds a button-press threshold as a button-press event. Sensor electronics coupled to the XY-position sensor and the Z-force sensor detects, as a button touch-press condition, the capacitive XY-position sensor sensing a button-touch event, substantially contemporaneous with the Z-Force sensor sensing a button-press event.