Graphical input apparatus for electrical equipment

摘要

A graphical input tablet is disclosed in which the lower surface of a sheet is spaced from the upper surface of a fixed member. Each or both surfaces are formed by parallel conductors but where only one surface is formed in this way the other surface is resistive. Currents are passed alternately through the surfaces to provide voltage gradients, and when a stylus is used to indicate a point, alternate co-ordinate signals for the point are obtained.