Detect and differentiate touches from different size conductive objects on a capacitive button

Abstract

Apparatuses and methods of capacitive buttons and detecting and differentiating touches from different size conductive objects on the capacitive buttons. One apparatus includes a capacitance-sensing circuit coupled to a capacitive button. The capacitive button includes a first sense element and a second sense element. The capacitance-sensing circuit is operative to measure signals from the first sense element and the second sense element with a sensing parameter (also referred to as tuning properties) set to a first value. The signals correspond to capacitances of the first sense element and second sense element. An inner perimeter of the first sense element is disposed to surround (at least in part) an outer perimeter of the second sense element. The apparatus further includes processing logic coupled to the capacitance-sensing circuit. The processing logic is operative to detect whether the first sense element is activated by a conductive object proximate to the capacitive button based on the measured signals. The processing logic detects whether the second sense element is activated by the conductive object proximate to the capacitive button based on the measured signals. The processing logic adjusts the first value to a second value for the sensing parameter when the second sense element is activated and the first sense element is not activated. The capacitance-sensing circuit is operative to measure an additional signal from the second sense element with the sensing parameter set to the second value when the second sense element is activated and the first sense element is not activated.