Hover position calculation in a touchscreen device

Abstract

A method is disclosed for calculating position of a conductive object hovering above a plurality of mutual capacitance sensors. The method begins by measuring capacitance on a plurality of mutual capacitance sensors, each mutual capacitance sensor represented as a unit cell in an array of unit cells. After measuring the capacitances, the method identifies a peak unit cell based on the measured capacitances and calculates an edge cutoff value from the measured capacitances. After the edge cutoff value is calculated, a plurality of unit cells with measured capacitance within a range defined by the edge cutoff value is selected and the position of the hovering conductive object calculated. A user interface device is disclosed that comprises a first plurality capacitance sensing electrodes disposed along a first axis of an array, a second plurality of capacitance sensing electrodes disposed along a second axis of an array, and a controller. The controller may be configured to calculate position of a conductive object hovering above a plurality of mutual capacitance sensors. The controller may measure capacitance on a plurality of mutual capacitance sensors, each mutual capacitance sensor represented as a unit cell in an array of unit cells. After measuring the capacitances, the controller may identify a peak unit cell based on the measured capacitances and calculate an edge cutoff value from the measured capacitances. After the controller calculates the edge cutoff value, it may calculate position based on unit cells within a range defined by the edge cutoff value.