Patent ID: 8692801

Claim:
A non-transitory machine-implemented method of determining where activated capacitance sensors are located on a capacitive-touch interactive screen comprising: a first step, the first step comprising: precharging each capacitance sensor in a group of N capacitance sensors to a distinct voltage V n ; electrically connecting all N capacitance sensors in parallel; transferring charge from all N sensors connected in parallel to a reference capacitor C ref ; converting the charge transferred to the reference capacitor C ref to a sensed voltage V sense ; wherein the sensed voltage V sense equals a single state; storing the single state; a second step, the second step comprising: repeating the first step K times; wherein the value of K is substantially less than the number of sensors N; a third step, the third step comprising: determining a capacitance C n for each capacitance sensor in the column of N capacitance sensors by solving an equation using sparse-activation compressive sensing, the equation given by: v n = Φ n ⁢ c n wherein Φ n = [ V 0 , n 0 … V M - 1 , n 0 ⋮ ⋱ ⋮ V 0 , n K - 1 … V M - 1 , n K - 1 ] c n = [ C 0 , n … C M - 1 , n ] T v n = [ v n 0 ⁢ ⁢ … ⁢ ⁢ v n K - 1 ] T wherein C m,n is the node capacitance of a capacitance sensor at the intersection of row m and column n; wherein m=(0, 1. . . , M−1); wherein an activated capacitance sensor on the capacitive-touch interactive screen is located where the capacitance C m,n of sensor (s) is different from the capacitance of capacitance sensors that are not activated on the capacitive-touch interactive screen.