| 摘要 |
<p>PURPOSE:To eliminate a code between a marker and another circuit by providing a switch, for which a tuning circuit is constituted when a pen body is abutted to the writing surface, etc., of a blackboard main body. CONSTITUTION:When the marker is operated on the writing surface of the blackboard main body, a switch 151 is operated and the tuning circuit, which is composed of a coil 152 and capacitors 153 and 154, is constituted. However, in such a case, an electric wave to have a prescribed frequency is received from an antenna coil in the blackboard main body side and the induced voltage of a prescribed frequency is generated in the tuning circuit. A current flows into the tuning circuit by this induced voltage and the electric wave of the almost same frequency as the prescribed frequency is transmitted from a coil 152. However, since the current is continued to flow without being rapidly attenuated even when the electric wave from the antenna coil is stopped, the induced voltage of the almost same frequency as the prescribed frequency is generated in the antenna coil. Accordingly, the usage of the marker can be discriminated in the blackboard main body side.</p> |
