A device for automatically producing a numerical representation of the location of any elemental area on a working surface, which device includes a matrix defining the working surface and composed of two mutually transverse sets of parallel conductive elements, the elements of one set being elastically deformable and the two sets being disposed parallel to one another and spaced apart by a small distance which permits any elastically deformable element of the one set to contact an element of the other set when subjected to a deforming pressure, the device further including a pulse generator for applying signal pulses to both sets of elements in such a manner that a pulse is present on only one set of elements at any given instant, and logic circuits each having one input connected to a respective element of one set, another input connected to a respective element of the other set, and an output at which a signal appears only when a pulse is applied to both of the elements to which its inputs are connected, this occurring when a pulse is applied to the elements of one set and one of the elements of the one set contacts one element of the other set.