| 摘要 |
<p>PURPOSE:To obtain coordinate information by detecting the phase of an electric field formed on a coordinate board, by using a diode switch circuit that applies selectively a voltage in the longitudinal and laternal directions of the coordinate blord and pi/2 out-of-phase sine-wave voltage generating circuits connected to the circuit. CONSTITUTION:Diodes 16 and 18, connected to resistance board 14 longitudinally and laterally, are applied with out-of-phase signals from sine-wave oscillator 10 and pi/2 out-of-phase sine-wave oscillator 12. When pen 20 coupling resistance board 14 with electrostatic capacity is placed on resistance board 14, the waveform of a differentiated earth voltage waveform is obtained from amplifying circuit 22 and sent to AND gates 30 and 32 via differentiating circuit 24 and zero-cross detector 26. From AND gates 28d and 28f of reference phase pulse generating circuit 28, reference phase pulses for separation into an X coordinate component and Y coordinate component are outputted and from integral amplifying circuits 34 and 36, coordinate position signals X and Y of the tip of pen 20 are also outputted.</p> |
