DEVICE FOR READING OUT COORDINATE.

摘要

A device for reading out coordinates which is provided with a part for reading out coordinates in which a plurality of exciting wire groups and a plurality of sensing wire groups are laid, a coordinate indicator which has a resonance circuit comprising a coil and a capacitor, and in which one or more series circuits each of which comprises a switch and a capacitor are connected in parallel with the resonance circuit, a first selecting circuit which selects successively the exciting wire groups, a second selecting circuit which selects successively the sensing wire groups, an exciting circuit which is connected with the first selecting circuit and feeds exciting signals, each having a frequency neighbouring the resonance frequency of the resonance circuit, to the exciting wire groups, an amplitude sensing circuit which is connected with the second selecting circuit and senses the amplitudes of induction signals induced in the sensing wire groups, a phase sensing circuit which senses the phases of the induction signals induced by the exciting signals, an amplitude storing means which stores the output of the amplitude sensing circuit, a phase storing means which stores the output of the phase sensing circuit, a controlling circuit which judges the states of the switches in the coordinate indicator according to the difference between the output of the amplitude sensing circuit and the information stored in the amplitude storing means and to the difference between the output of the phase sensing circuit and the information stored in the phase storing means.