Coordinate reading system for detecting operation states of numerous switches

A coordinate reading system having a coordinate reading system body and a coordinate indicator comprising:

• the coordinate reading system body including
• a first group of sense lines having a plurality of sense lines,
• a second group of sense lines having a plurality of sense lines,
• an excitation means for outputting a plurality of frequencies as excitation signals,
• a selecting means for obtaining an excitation signal among the excitation signals outputted from the excitation means and supplying the obtained excitation signal to the first group of sense lines,
• a phase detection means for detecting a phase contrast between the excitation signal and an induced signal induced on the second group of sense lines and corresponding to the obtained excitation signal, and
• a switch identifying means for identifying one or more pressed switches among switches provided on the coordinate indicator from a phase contrast signal outputted by the phase detection means or from the phase contrast signal and information based on the excitation signal;
• and
• the coordinate indicator including
• a resonant means including one or more resonant circuits capable of resonating with one of the excitation signals corresponding to a plurality of the frequencies respectively,
• a means including a plurality of devices for modifying resonant frequencies of the resonant means by being connected thereto, and
• a switching means including a plurality of switches for connecting at least one of the devices to the resonant means.