Synaptics Incorporated
USING ELECTRICAL RESISTANCE TO ESTIMATE FORCE ON AN ELECTRODE DURING TEMPERATURE CHANGES

Abstract:

A processing system including processing circuitry and sensor circuitry configured to obtain first resistance measurements of a plurality of sensor electrodes that compose a surface of an input device. The processing circuitry measures, in a first time interval, first values of electrical resistances of the electrodes. The processing circuitry calculates, from the first values, a first rate of change in the resistances, and measures, in a subsequent second time interval, second values of the electrical resistances. The processing circuitry calculates, from the second values, a second rate of change in the electrical resistances, as well as calculates, over the second time interval and based on the first rate of change, projected values of electrical resistances. The processing circuitry filters the projected values from the second values of the electrical resistances. The processing circuitry calculates, and reports, final values for the force over the second time interval using the filtered measurement.