| 摘要 |
<p>PURPOSE:To identify the state without deteriorating the operability of a coordless position indicator by providing an antenna coil around a coordinate input range and a tuning circuit having a prescribed tuning frequency on the position indicator respectively. CONSTITUTION:A tablet main body 12 is connected to a position detection circuit 3 and an antenna coil 13 provided around the coordinate input range 14 is connected to a timing control circuit 4. A radio wave sent fro the antenna coil 13 is received by a tuning circuit 22 of the position indicator 2 and an induced voltage having a frequency nearly the same as that of a signal fed to the antenna coil 13 is generated in the turning circuit 22. In this case, the reflected radio wave is sent from the coil in the circuit 22 based on the current flowing to the tuning circuit 22, received by the antenna coil 13 and the induced voltage generated in the antenna coil shows a value corresponding to the distance between the position indicator 2 and the antenna coil 13. Thus, any complicated signal generating circuit or battery is not required and the position indicator with very excellent operability is obtained.</p> |
