A touch sensor includes a touch panel including driving lines and sensing lines and having node capacitors between neighboring or overlapping driving lines and sensing lines, a driving unit configured to modulate driving signals using a direct sequence spread spectrum technique or scheme and simultaneously drive two or more of the driving lines using the modulated driving signals, and a sensing unit configured to demodulate the signals from the sensing lines using the direct sequence spread spectrum method and generate demodulated signals.
1. A touch sensor comprising:
a touch panel including driving lines and sensing lines and having node capacitors between neighboring driving lines and sensing lines;
a driving unit configured to modulate driving signals using a direct sequence spread spectrum technique or scheme and simultaneously drive two or more of the driving lines using the modulated driving signals, wherein the driving unit multiplies the driving signals by first pseudo-random binary sequences and outputs the modulated driving signals, a period of the first pseudo-random binary sequences is shorter than that of the driving signals, and a probability of each of the first pseudo-random binary sequences is 1 during a driving sample period of the two or more driving lines; and
a sensing unit configured to demodulate the signals from the sensing lines using the direct sequence spread spectrum technique or scheme and generate demodulated signals.
2. The touch sensor according to claim 1 , wherein the first pseudo-random binary sequences have different values.
3. The touch sensor according to claim 1 , wherein:
the sensing unit multiplies the signals received by the sensing lines by second pseudo-random binary sequences and generates the demodulated signals, and
each of the second pseudo-random binary sequences is identical to any one of the first pseudo-random binary sequences.
4. The touch sensor according to claim 1 , wherein the sensing unit includes:
an amplifier unit configured to amplify the signals from the sensing lines and output amplified signals;
an analog/digital converter unit configured to convert the amplified signals to digital signals; and
a demodulator unit configured to demodulate the digital signals using the direct sequence spread spectrum technique or scheme and generate the demodulated signals.
5. The touch sensor according to claim 4 , wherein the sensing unit further includes an integrator unit configured to integrate the demodulated signals and generate integrated signals.
6. The touch sensor according to claim 5 , wherein:
the sensing unit further includes a first calculator unit configured to calculate a difference between each of the integrated signals and a reference digital signal and generate digital output signals.
7. The touch sensor according to claim 6 , further comprising a second calculator unit configured to multiply a digital voltage by a reference gain to generate the reference digital signal.
8. The touch sensor according to claim 7 , wherein the digital voltage is a digital version of an analog reference voltage, and the reference gain is a gain of the amplifier unit when the touch panel is not touched.
9. The touch sensor according to claim 4 , wherein:
the demodulator unit includes a plurality of demodulators,
each of the plurality of modulators multiplies each digital signal by any one of the second pseudo-random binary sequences and generates the demodulated signal, and
each of the second pseudo-random binary sequences is identical to any one of the first pseudo-random binary sequences.
10. The touch sensor according to claim 4 , wherein the sensing unit further includes a digital signal processor configured to detect a change in capacitances of the sensing nodes from the integrated signals.
11. The touch sensor according to claim 4 , wherein the amplifier unit includes:
an operational amplifier including a first input terminal connected to any one of the sensing lines, a second input terminal connected to a ground potential, and an output terminal configured to output an amplified signal, and
a feedback capacitor connected between the output terminal and the first input terminal of the operational amplifier.
12. The touch sensor according to claim 1 , wherein:
the driving unit includes driving circuits configured to drive the driving lines, and
each of the driving circuits includes:
a random number generator configured to generate a first pseudo-random sequence; and
a modulator configured to multiply a driving signal by the first pseudo-random binary sequence and output a modulated driving signal.
13. A touch sensor comprising:
a touch panel including driving lines and sensing lines and having node capacitors between neighboring or overlapping driving lines and sensing lines, the driving lines including a plurality of groups, each of the plurality of groups including two or more driving lines;
a driving unit configured to modulate driving signals using a direct sequence spread spectrum technique or scheme and simultaneously drive two or more driving lines in each of the plurality of groups using the modulated driving signals, wherein the driving unit multiplies each of the driving signals by any one of different first pseudo-random binary sequences to generate the modulated driving signals; and
a sensing unit configured to generate amplified signals by amplifying the signals on or from the sensing lines, generate digital signals from the amplified signals, generate demodulated signals by demodulating the digital signals using the direct sequence spread spectrum technique or scheme, generate integrated signals by integrating the demodulated signals, calculate a difference between each of the integrated signals and a reference digital signal, and generate digital output signals, and
a calculator unit configured to multiply a digital voltage by a reference gain to generate the reference digital signal.
14. The touch sensor according to claim 13 , wherein the digital signal is a digital version of an analog reference voltage, and the reference gain is a gain of the amplified signal when the touch panel is not touched.
15. The touch sensor according to claim 13 , wherein the driving unit sequentially drives the plurality of groups.
16. A touch sensor, comprising:
a touch panel including driving lines and sensing lines and having node capacitors between neighboring driving lines and sensing lines;
a driving unit configured to modulate driving signals using a direct sequence spread spectrum technique or scheme and simultaneously drive two or more of the driving lines using the modulated driving signals, wherein the driving unit multiplies the driving signals by first pseudo-random binary sequences and outputs the modulated driving signals; and
a sensing unit configured to demodulate the signals from the sensing lines using the direct sequence spread spectrum technique or scheme and generate demodulated signals, wherein the sensing unit multiplies the signals received by the sensing lines by second pseudo-random binary sequences and generates the demodulated signals, and each of the second pseudo-random binary sequences is identical to any one of the first pseudo-random binary sequences.