Patent ID: 7218314

Claim:
A coordinate input device comprising: a coordinate detector including: a first insulating layer which is transparent; a second insulating layer which is transparent and which is formed on a lower surface of the first insulating layer; a first electrode layer having a plurality of transparent electrodes formed in parallel and between the lower surface of the first insulating layer and an upper surface of the second insulating layer; a second electrode layer having a plurality of transparent electrodes which are aligned in parallel and which extend in a direction orthogonal to the transparent electrodes of the first electrode layer, the second electrode layer being formed on a lower surface of the second insulating layer; and a third insulating layer which is transparent and which is formed on a lower surface of the second electrode layer, and a controller which is electrically connected to the two electrode layers of the coordinate detector so as to drive and control the electrode layers and which has a correction circuit to remove electrostatic capacitance noise that disturbs the coordinate detector, the controller including a reference signal storing circuit to store a reference signal, which is a detection signal obtained by scanning the electrodes of the first electrode layer and the second electrode layer while no operation is performed and a correction value calculating circuit to subtract the reference signal from a detection signal while an operation is performed, thereby correcting the detection signal during the operation.