Synaptics Incorporated
Self-referenced capacitive force sensor

Abstract:

A force sensing apparatus includes a first layer having a first electrode disposed thereon, a second layer having a second electrode disposed thereon, and a spacer layer configured to transfer an input force exerted on the first layer to the second layer. The spacer layer causes a change in a separation distance between the first electrode and the second electrode in response to the input force. The force sensing apparatus further includes processing circuitry to detect a change in capacitive coupling between the first electrode and the second electrode based on the change in separation distance, and to determine force information about the input force based at least in part on the detected change in capacitive coupling.