1. A sensor for capacitively sensing the position in a continuous range of positions of an object on a surface of an input device, which comprises: an array of electrodes on said surface; an insulating layer covering said electrodes; means connected to said electrodes for measuring a capacitance value for each said electrode; means responsive to said measuring means for comparing said capacitance values with a first preset threshold and, if at least one of said capacitance values exceeds said first preset threshold, for calculating the position of a centroid of capacitance for said array from said measured capacitance values, said first preset threshold being set at a capacitance value that is exceeded for a given electrode only when said object is close to or touching said given electrode, said centroid of capacitance being the first moment of the distribution of said capacitance values in said array and representing substantially the position of said object on said surface; and means responsive to said calculating means and connected to utilizing means for sending said centroid of capacitance position to said utilizing means.