trough like semicircular cross sections this bottom contour of the channels is continued right into the intersection so that balls when displaced by key depressing will be retained in the respective channel and not be deflected into any intersecting channel so that the each key is positively identifiable by two switch closings the switches being disposed for actuation at one end each of these channels application_number US 88315178 A description it is an object of the present invention to eliminate the problem outlined above and to provide a new and improved keyboard structure using displacement bodies in which such bodies are displaced with certainty in the desired manner it is a particular object of the present invention to improve keyboard structures which are provided with intersecting row channels and column channels and switching means adjacent one end of each of the channels to be actuated by the displacement of displacement bodies in the channels whereby such displacement is initiated upon pressing of a key of the board in accordance with the preferred embodiment of the invention it is suggested to contour the channels at least at near and in the intersections and at least as far as the bottom of a channel is concerned to have concavely shaped at at least partially matching contours with the displacement bodies so that the bodies are fully guided right up to as well.