| 摘要 |
A user input system ( 1 ), comprising a coil ( 44 ) for generating an alternating magnetic field, a cordless pen ( 9 ), and a capacitive current measuring arrangement or an electric field sensing arrangement. The cordless pen ( 9 ) comprises a resonant circuit ( 34 ), a conductive housing ( 28 ) and a conducting tip ( 36 ). The alternating magnetic field induces an alternating voltage in the resonant circuit ( 34 ), which is coupled to the conducting tip ( 36 ). The capacitive current measuring arrangement comprises a resistive sheet ( 40 ) and current measuring means ( 42 ) arranged to measure a capacitive current flowing from the conducting tip ( 36 ) to the resistive sheet ( 40 ). The electric field sensing arrangement comprises an electric field sensing reception electrode ( 47 ) and current sensing circuitry ( 48 ) for determining a current excited in the electric field sensing reception electrode ( 47 ) by an electric field generated by the conducting tip ( 36 ). In each case the currents are sensed at plural locations and the differing magnitudes compared to determine a position of the conducting tip ( 36 ) relative to the plural locations. The system may also be adapted to sense a user's finger ( 8 ). The user input system ( 1 ) may be incorporated in a display device, for example an active matrix liquid crystal display device ( 4 ). |
