Patent ID: 7940063

Claim:
A coordinate detecting device comprising: a resistive film disposed on a quadrangular substrate made of an insulating material; a power source configured to apply a voltage to the resistive film; four electrodes, each of which is connected to the power source and individually disposed in one of four corners of the resistive film; four switches, each of which is individually disposed between the power source and one of the electrodes; four ammeters, each of which is configured to measure a current flowing through a corresponding one of the electrodes; and a grounded conductive film configured to detect coordinates of a contact point on the resistive film when the conductive film is brought in contact with the resistive film; wherein the voltage is applied sequentially to the electrodes by opening and closing the switches, when the conductive film is brought in contact with the resistive film, each of the ammeters sequentially measures the current flowing through the corresponding one of the electrodes, and the coordinates of the contact point are detected based on positions of the electrodes and resistances obtained using currents measured by the ammeters.