System and method for detecting finger touch and stylus

PURPOSE: To provide a finger touch and stylus detection system which is to be used on the surface of a display device. CONSTITUTION: An overlay 16 having horizontal and vertical transparent conductors is coupled to another element of a system through busses 60 and 90 having the minimum number of bus wires. A control processor 100 issues a command which couples transparent conductors to a capacity measuring instrument 128 for the purpose of determining the finger position and issues a command which couples transparent conductors to a radiation measuring instrument 122 for the purpose of determining the position of a stylus 20. The radiation stylus may be provided with a spherical antenna, which receives an overlay signal independently of the angle of stylus holding, to improve the system. Further, a contact detection mode is added to eliminate a false stylus position measured between strokes at the time when the stylus is close to the overlay but doesn't come into contact with it. COPYRIGHT: (C)1992,JPO