Touch sensor and a display device including the same
A touch sensor including: a touch sensing area including driving electrodes and sensing electrodes; a driving signal generator which determines phases of driving signals based on a reference code and supplies the driving signals to the sensing electrodes, wherein the driving signals are sine waves; and a touch processor which receives sensing signals according to the driving signals from the sensing electrodes and determines a touch position based on the sensing signals and the reference code, wherein the driving signal generator controls the phases of the driving signals by updating the reference code at a predetermined time point.
1. A touch sensor, comprising:
driving electrodes and sensing electrodes for touch sensing;
a driving signal generator which supplies driving signals to the sensing electrodes based on a reference code; and
a processor which receives a sensing signal from the sensing electrodes and determines a touch position based on the sensing signal and the reference code;
wherein the driving signal generator updates the reference code at a predetermined time point, the time point is determined so that a phase delay of the driving signal to the time point is less than π/4.
2. The touch sensor of claim 1 , wherein the driving signal generator determines phases of the driving signals based on the reference code, and generates the driving signals using the determined phases.
3. The touch sensor of claim 1 , wherein the sensing signal received from the processor corresponds to the driving signals supplied to the sensing electrodes.
4. The touch sensor of claim 1 , wherein the driving signal generator controls the phases of the driving signals by updating the reference code at the time point.
5. The touch sensor of claim 1 , wherein the driving signal generator supplies the driving signals in parallel to driving electrodes included in a first group of the driving electrodes during a first driving period.
6. The touch sensor of claim 5 , wherein the driving signal generator comprises:
a sine wave generator which generates sine wave signals;
a code generator which outputs a first phase or an inverse phase of the first phase of each of the sine wave signals supplied from the sine wave generator in response to the reference code as the driving signals; and
a storage which stores a plurality of orthogonal codes, and
wherein the code generator selects one of the orthogonal codes as the reference code at the predetermined time point.
7. The touch sensor of claim 6 , wherein the driving signal generator supplies the driving signals in parallel to driving electrodes included in a second group of the driving electrodes during a second driving period, and
wherein a waveform of a first driving signal supplied to a first driving electrode of the first group during the first driving period is different from a waveform of a second driving signal supplied to a first driving electrode of the second group during the second driving period.
8. The touch sensor of claim 6 , wherein the first driving period includes a plurality of unit periods in which the driving signals corresponding to the reference code are supplied to the first group.
9. The touch sensor of claim 8 , wherein the driving signals corresponding to a first reference code are output in at least one of the unit periods of the first driving period, and the driving signals corresponding to a second reference code are output in at least another one of the unit periods of the first driving period.
10. The touch sensor of claim 5 , wherein the processor comprises:
an analog signal processor which generates output signals by removing noise from the sensing signals;
an analog digital converter which converts the output signals to digital sensing signals; and
a digital processor which calculates sensed capacitances by demodulating the digital sensing signals using the reference code.
11. The touch sensor of claim 1 , wherein the driving signal comprise a sine wave, and at least one phase of the driving signals supplied to the first group in a period of the sine wave in the first driving period is opposite to phases of the rest of the driving signals supplied to the first group in the period.
12. The touch sensor of claim 11 , wherein the reference code includes a matrix of 1 values and −1 values, the value 1 and the value −1 correspond to sine waves having opposite polarities, and the reference code is an orthogonal code.
13. The touch sensor of claim 12 , wherein the number of rows of the matrix corresponds to the number of the driving electrodes in the first group, and
the number of columns of the matrix corresponds to the number of times the cycle of the sine wave is repeated.
14. A display device, comprising:
a display panel including pixels;
driving electrodes and sensing electrodes disposed on the display panel;
a driving signal generator which supplies driving signals to the sensing electrodes based on a reference code; and
a processor which receives a sensing signal from the sensing electrodes and determines a touch position based on the sensing signal and the reference code;
wherein the driving signal generator updates the reference code at a predetermined time point, the time point is determined so that a phase delay of the driving signal to the time point is less than π/4.
15. The display device claim 14 , wherein the driving signal generator determines phases of the driving signals based on the reference code, and generates the driving signals using the determined phases.
16. The display device claim 14 , wherein the sensing signal received from the processor corresponds to the driving signals supplied to the sensing electrodes.
17. The display device claim 14 , wherein the driving signal generator controls the phases of the driving signals by updating the reference code at the time point.
18. The display device of claim 14 , wherein the driving signal generator supplies the driving signals in parallel to driving electrodes included in a first group of the driving electrodes during a first driving period.
19. The display device of claim 18 , wherein the reference code includes a matrix including 1 or −1 as a value thereof, and
the value 1 and the value −1 represent sine waves having opposite polarities.
20. The display device of claim 19 , wherein the driving signal generator comprises:
a sine wave generator which generates sine wave signals; and
a code generator which outputs a first phase or an inverse phase of the first phase of the sine wave signals supplied from the sine wave generator in response to the reference code as the driving signals.