| 摘要 |
<p>The object of the present invention is to enable detecting operation states of numerous switches in a cordless coordinate reading system. The coordinate reading system body is provided with the switching circuit 5 for selecting the excitation signal, so that one of the groups of sense lines 1, S1 can be excited with a plurality of frequencies. The coordinate indicator 20 is provided with the resonant circuit and the groups of devices for setting frequency 21, 22 which modify the resonance frequency of the resonant circuit in accordance with the press of the switch, enable the resonant circuit to resonate with any one of a plurality of the resonance frequencies, and further slightly modify the resonance frequency. Further, the coordinate reading system body is provided with the circuit 8 for detecting the phase contrast between the induced signal from the coordinate indicator 20 and the excitation signal. Thereby, it is possible to detect the switch which is pressed down among the numerous switch from the excitation frequencies and the phase contrast data. <IMAGE></p> |
