Elementary cell combinable to form dot matrix displays

An elementary cell combinable to form dot matrix displays, in which a plurality of plates of non-magnetic insulating material, at least one of which is in contact with a plate of high magnetic permeability, are arranged to define a seat for housing a sphere provided internally with a permanent magnet, said plates housing a plurality of energizable magnetic poles, said sphere having a polychromatic outer surface divided into sectors, at least one of said plates being provided with a window displaying a portion of said sphere and with a transparent closure element, characterised in that the permanent magnet contained within said sphere comprises composite spatial-surface geometrical shapes in the form of depressions, reliefs and contours, said geometrical shapes being in correlation with other similar shapes on said energizable magnetic poles, said magnet interacting with said plurality of energizable poles and with said geometrical shapes to cause said sphere to assume a combination of n positions where n is even and is greater than or equal to 2.