Patent ID: 6239788
Filing Date: 2001-05-29
Classification: G02F,G06F,G09G

Abstract:
A coordinate input device, comprising:a tablet including first electrodes that are parallel to one another at specified intervals, and second electrodes also parallel to one another at specified intervals, but in a direction crossing the direction of the first electrodes, wherein the first electrodes are insulated from the second electrodes;a DC voltage generating means for generating a DC power voltage;a control means for outputting a detection control signal used to detect designated coordinates on the tables;an AC applying means for generating a superimposition voltage and a superimposition detection control signal, by superimposing an AC voltage of identical phase and amplitude on both the DC power voltage and the detection control signal;an electrode drive means for selecting ones among the first and second electrodes based on the superimposition detection control signal, and for applying the superimposition voltage to non-selected electrodes; anda coordinate detecting means for detecting a current flowing through the selected electrode and detecting the designated coordinates on the tablet based on this current.