| 摘要 |
<p>In a wireless coordinate reader a switch circuit, which is formed by connecting a plurality of series circuits each consisting of a switch (13a, 13b, 13c ...) and a resistor (14a, 14b, 14c ...) in parallel with each other and connecting a capacitor (15) in series with one of the ends of this parallel circuit, is connected in parallel with a resonance circuit consisting of a coil (11) and a capacitor (12) to constitute a coordinate indicator (10). The coordinate reader comprises an amplification detection circuit (7) for detecting the amplitude of an induction signal (is) induced on a sense line, a phase detection circuit (8) for detecting the phase, and a control circuit (9) for judging the state of switches of the coordinate indicator (10) from the detected amplitude signal (as) and phase signal (ps). The amplitude of a specific induction signal (is) is corrected by coordinate data while using it as height data. The switch state is judged after the phase signal (ps) is corrected in order to detect correctly the switch state. <IMAGE> <IMAGE></p> |
