| 摘要 |
<p>PURPOSE:To transmit the switch information of a coordinate indicator to a tablet with high accuracy by turning a switching means on and superimposing the switch information on the amplitude of an alternating field while the alternating field is generated from the coordinate indicator. CONSTITUTION:When a cursor 2 is positioned on the read surface 6 of the tablet 4 and at least one of optional push button switches 18-21 is pushed, an alternating current from an oscillation circuit 24 is modulated to an amplitude pattern set by the pushed push button switches 18-21 at an amplitude modulation circuit 24 and is supplied to a pointer coil 3. Thus, the switch information which changes corresponding to the amplitude pattern is superimposed on the amplitude of the alternating field generated at the pointer coil 3. The alternating field is received by the respective sensing coils 7 and 8 of the tablet 4 and the electromotive force of sizes corresponding to respective distances from the pointer coil 3 is respectively induced. The electromotive force is amplified at an amplifier circuit 13 and amplitude demodulated at a demodulator 25, the amplitude pattern is decoded and the push button switch which was turned on is discriminated.</p> |
