Force sensing using capacitive touch surfaces

A touch-sensitive input device comprising:

• a glass-plus-sensor module including:
• a cover glass including a top surface and a bottom surface;
• and
• at least two electrodes attached to the bottom surface of the cover glass, the at least two electrodes having an associated self-capacitance;
• an optically clear adhesive layer (OCA) layer;
• a display device having a top surface and a bottom surface;
• and
• a ground plane attached to the bottom surface of the display device;
• the OCA layer attaching the bottom surface of the cover glass to the top surface of the display device;
• and
• the glass-plus-sensor module bending towards the display device at a point of contact of a conductive element with the top surface of the cover glass, the bending changing, for each of the at least two electrodes, the self-capacitance associated with the electrode, and a calculation of a force applied by the contact of the conductive element with the top surface of the cover glass being based on the change in self-capacitance for each electrode.

A computing device comprising:

• at least one controller;
• and
• a touch-sensitive input device configured to facilitate interaction by a user with a graphical user interface (GUI), the touch-sensitive input device comprising:
• a glass-plus-sensor module including:
• a cover glass including a top surface and a bottom surface;
• and
• at least two electrodes attached to the bottom surface of the cover glass, the at least two electrodes having an associated self-capacitance;
• a display device having a top surface and a bottom surface, the computing device being configured to render the GUI on the display device;
• an optically clear adhesive layer (OCA) layer attaching the bottom surface of the cover glass to the top surface of the display device;
• and
• a ground plane attached to the bottom surface of the display device,
• wherein the at least one controller and the touch-sensitive input device are collectively configured to:
• detect contact of a conductive element with the top surface of the cover glass, and based on the detected contact;
• determine, for each of the at least two electrodes, a self-capacitance associated with the electrode;
• and
• calculate a force applied by the contact of the conductive element with the top surface of the cover glass based on the determined self-capacitance associated with each of the at least two electrodes.