Patent ID: 8564565
Filing Date: 2013-10-22
Classification: G06F

Abstract:
1. A method for providing a cleaned signal in a capacitive touch sensor, the capacitive touch sensor including a first array of conductors and a second array of conductors, wherein the conductors in the first array are arranged substantially in parallel with one another, and the conductors in the second array are arranged substantially in parallel with one another, and wherein the conductors in the first array are positioned substantially perpendicular to the conductors in the second array to form a matrix, the method comprising: determining a phase of periodic noise on an input of the capacitive touch sensor; generating a periodic excitation signal having a phase that is locked to the determined phase of the periodic noise; applying the periodic excitation signal to an excited conductor in the first array; while the excitation signal is applied, detecting a response signal on a responding conductor in the second array, and generating, based on the detected response signal, a value indicative of a measured capacitance between the excited conductor and the responding conductor; accessing a threshold value; determining whether the response signal corresponds to a touch based on a difference between the value and the threshold value; and producing a signal reflecting results of the determination of whether the response signal corresponds to a touch.