Patent ID: 8810546
Filing Date: 2014-08-19
Classification: G06F

Abstract:
1. An apparatus comprising a processing device configurable to calculate a frequency response of a touch panel coupled to the processing device, wherein the processing device comprises: a capacitance-sensing circuit to measure signals from the touch panel; and a frequency-response calculator, wherein the frequency-response calculator is configured to measure a frequency response of the touch panel, wherein the processing device is configured to select an operating frequency of the touch panel in view of the measured frequency response, wherein the operating frequency is a scanning frequency used by the capacitance-sensing circuit to measure additional signals from the touch panel, wherein the frequency response calculator comprises a time-constant calculator, wherein the time-constant calculator is configured to vary window durations during which the capacitance-sensing circuit measures the signals from the touch panel, wherein there is a dependence between a charge measured by the capacitance-sensing circuit and the window durations, and wherein the time-constant calculator is further configured to calculate a time constant from analysis of the dependence between the measured charge within the varied window durations.