TOUCHSCREEN DEVICE AND TOUCH SENSING METHOD
A touchscreen device may include a panel unit including a plurality of first electrodes and a plurality of second electrodes; a driving circuit unit sequentially applying a driving signal having a predetermined period to the plurality of first electrodes; a sensing circuit unit detecting levels of capacitance from the plurality of second electrodes; and a driving voltage generating unit generating a driving voltage. The driving voltage generating unit adjusts a level of the driving voltage depending on a detected voltage which is detected in a first electrode, to which the driving signal is applied, among the plurality of first electrodes in a calibration section.
1 . A touchscreen device comprising:
a panel unit including a plurality of first electrodes and a plurality of second electrodes;
a driving circuit unit sequentially applying a driving signal having a predetermined period to the plurality of first electrodes;
a sensing circuit unit detecting levels of capacitance from the plurality of second electrodes; and
a driving voltage generating unit generating a driving voltage,
wherein the driving voltage generating unit adjusts the driving voltage depending on a detected voltage which is detected from a first electrode, to which the driving signal is applied, among the plurality of first electrodes in a calibration section.
2 . The touchscreen device of claim 1 , wherein the sensing circuit unit detects the levels of capacitance from the plurality of second electrodes after the calibration section ends.
3 . The touchscreen device of claim 1 , wherein the driving voltage generating unit maintains the driving voltage set at the end of the calibration section until the next calibration section starts.
4 . The touchscreen device of claim 1 , wherein the driving voltage generating unit includes:
a detecting unit detecting the detected voltage;
a driving voltage adjusting unit adjusting a set voltage depending on the detected voltage; and
a low-dropout (LDO) regulator generating the driving voltage depending on the set voltage.
5 . The touchscreen device of claim 4 , wherein the driving voltage generating unit further includes a boosting unit boosting the driving voltage generated by the LDO regulator.
6 . The touchscreen device of claim 5 , wherein the boosting unit includes a charge pump circuit.
7 . The touchscreen device of claim 4 , wherein the detecting unit includes a plurality of detectors disposed between each of the plurality of first electrodes and a ground, each of the plurality of detectors including a resistor element and a switching element connected to each other in series.
8 . The touchscreen device of claim 7 , wherein the switching element connected to the first electrode, to which the driving signal is applied, among the plurality of first electrodes performs a switching-on operation in the calibration section.
9 . The touchscreen device of claim 4 , wherein the driving voltage adjusting unit includes:
a comparing unit comparing the detected voltage and a predetermined reference voltage with each other; and
a driving voltage setting unit adjusting the set voltage depending on a comparison result of the comparing unit.
10 . The touchscreen device of claim 9 , wherein the comparing unit outputs the comparison result once per period of the driving signal.
11 . The touchscreen device of claim 10 , wherein the comparing unit includes:
a first operational amplifier comparing the detected voltage and a first reference voltage with each other; and
a second operational amplifier comparing the detected voltage and a second reference voltage with each other.
12 . The touchscreen device of claim 11 , wherein the detected voltage is applied to non-inverting terminals of the first and second operational amplifiers,
the first and second reference voltages are applied to inverting terminals of the first and second operational amplifiers, respectively, and
the first reference voltage is higher than the second reference voltage.
13 . The touchscreen device of claim 9 , wherein the driving voltage setting unit adjusts the set voltage depending on the comparison result according to a preset period.
14 . The touchscreen device of claim 9 , wherein the driving voltage setting unit raises or lowers a level of the set voltage by a preset level in a stepwise manner, depending on the comparison result.
15 . The touchscreen device of claim 9 , wherein the set voltage which is set at the time of an initial operation of the driving voltage setting unit is lower than a target level of the driving voltage.
16 . The touchscreen device of claim 1 , further comprising a signal converting unit converting the level of capacitance into a digital signal.
17 . The touchscreen device of claim 16 , wherein a touch is determined from the digital signal output from the signal converting unit.
18 . A touch sensing method, comprising:
generating a driving voltage;
applying a driving signal having a predetermined period to a plurality of first electrodes;
adjusting the driving voltage depending on a detected voltage which is detected in a first electrode to which the driving signal is applied among the plurality of first electrodes; and
detecting levels of capacitance from a plurality of second electrodes intersecting with the first electrode to which the driving signal is applied.
19 . The touch sensing method of claim 18 , wherein the levels of capacitance are detected after the driving voltage is adjusted.
20 . The touch sensing method of claim 18 , wherein the adjusting of the driving voltage includes:
detecting the detected voltage;
comparing the detected voltage and at least one reference voltage with each other;
adjusting a set voltage depending on a comparison result between the detected voltage and the reference voltage; and
changing the driving voltage depending on the set voltage.
21 . The touch sensing method of claim 20 , wherein the detected voltage is detected from a resistor element connected to the first electrode to which the driving signal is applied, among a plurality of resistor elements connected to the plurality of first electrodes, respectively.
22 . The touch sensing method of claim 20 , wherein the reference voltage includes first and second reference voltages that are preset, and
each of the first and second reference voltages is compared with the detected voltage.
23 . The touch sensing method of claim 20 , wherein the comparison result between the detected voltage and the reference voltage is output once per period of the driving signal.
24 . The touch sensing method of claim 20 , wherein the set voltage is adjusted depending on the comparison result according to a preset period.
25 . The touch sensing method of claim 20 , wherein a level of the set voltage is raised or lowered by a preset level in a stepwise manner, depending on the comparison result.
26 . The touch sensing method of claim 20 , wherein the set voltage which is set at the time of initial adjustment of the driving voltage is lower than a target level of the driving voltage.