Coordinate input device and display device including the same
A coordinate input device includes: a coordinate input unit having a plurality of first detection electrodes and a plurality of second detection electrodes; an electrode drive circuit that applies a drive signal to one or more of the detection electrodes; a detection circuit that detects a signal of the first and/or second detection electrode; a selection circuit for selecting one or more of the detection electrodes to which the drive signal is not applied from among the detection electrodes which are disposed in parallel to the detection electrodes to which the drive signal is applied, as a reference electrode; a detection circuit for detecting a signal of the selected reference electrode; an input coordinate computing circuit for correcting a detection result of the detection circuit on the basis of the detected capacitance of the reference electrode and for calculating an input coordinate from the corrected detection result.
1. A display device with a coordinate input device comprising:
a display panel,
a plurality of first detection electrodes disposed in parallel to each other;
a plurality of second detection electrodes intersecting the first detection electrodes;
a reference signal wire;
an electrode drive circuit configured to apply a drive signal to one or more of the first detection electrodes;
a switching circuit configured to select either a first connection of the electrode drive circuit and the first detection electrode or a second connection of the reference signal wire and the first detection electrode; and
a detection circuit configure to detect a signal of the second detection electrode generated by the drive signal;
wherein the detection circuit detects a signal of the reference signal wire as a noise signal of the first detection electrode which is electrically connected with the reference signal wire by the second connection, and
further comprising an input coordinate computing circuit configured to correct a detection result of the detection circuit on the basis of the detected noise signal, and to calculates an input coordinate from the corrected detection result.
2. The display device according to claim 1 , wherein the first detection electrode which connects to the reference signal wire by the second connection is disposed in parallel to the vicinity of the first detection electrode to which the drive signal is applied.
3. The display device according to claim 1 ,
wherein the detection circuit includes a circuit configured to measure currents or voltages of the plurality of second detection electrodes generated by the drive signal.
4. The display device according to claim 3 ,
wherein the circuit for correcting a detection result includes a circuit configured to calculate a correction value within a predetermined range by adding or subtracting a predetermined value to or from the detection result from the reference signal wire.
5. A display device with a coordinate input device comprising:
a display panel;
a plurality of first detection electrodes disposed in parallel to each other,
a plurality of second detection electrodes intersecting the first detection electrodes,
a reference signal wire;
an electrode drive circuit configured to apply a drive signal to one or more of the first detection electrodes,
a switching circuit configured to select either a first connection of the electrode drive circuit and the first detection electrode or a second connection of the reference signal wire and the first detection electrode; and
a detection circuit configured to detect a signal of the second detection electrode charged by the drive signal and electrically connecting with the reference signal wire,
wherein
the switching circuit selects the first detection electrode as a reference electrode by the second connection,
the detection circuit detects a signal of the reference electrode as a noise signal,
a correcting circuit corrects a detection result of the detection circuit on the basis of the detected the noise signal of the reference electrode, and
further comprising an input coordinate computing circuit that calculates an input coordinate from the corrected detection result.
6. The display device according to claim 5 , wherein the reference electrode is the first detection electrode which is disposed parallel to the vicinity of the first detection electrode to which the drive signal is applied.
7. The display device according to claim 5 ,
wherein the detection circuit includes a circuit configure to measure currents or voltages of the plurality of second detection electrodes as the signal of the second detection electrodes.
8. The display device according to claim 7 ,
wherein the corrected detection result includes a correction value within a predetermined range by adding or subtracting a predetermined value to or from the detection result from the reference electrode.