Capacitance sensing apparatus and method, and touch screen apparatus
There is provided a capacitance sensing apparatus including: a driving circuit unit applying a driving signal to a first capacitor; a first integrating circuit unit including a second capacitor charged by a change in capacitance generated in the first capacitor based on the driving signal to generate a first output voltage; and a second integrating circuit unit including a third capacitor charged by a change in capacitance generated in the second capacitor to generate a second output voltage, wherein a level of the second output voltage is changed at least twice during a single period of the driving signal applied to the first capacitor.
1. A capacitance sensing apparatus comprising:
a driving circuit unit applying a driving signal to a first capacitor;
a first integrating circuit unit including a second capacitor being charged by a change in capacitance generated in the first capacitor based on the driving signal, the first integrating circuit unit generating a first output voltage; and
a second integrating circuit unit including a third capacitor charged by a change in capacitance generated in the second capacitor to generate a second output voltage,
a level of the second output voltage being changed at least twice during a single period of the driving signal applied to the first capacitor, and
the second capacitor being charged and discharged twice during a single period during which the first capacitor is charged and discharged once by the driving signal, wherein a level of the first output voltage is repeatedly: decreased, held, increased, held, increased, held, decreased, and held consecutively.
2. The capacitance sensing apparatus of claim 1 , wherein the level of the second output voltage is increased when a level of the first output voltage is decreased.
3. The capacitance sensing apparatus of claim 1 ,
wherein the first integrating circuit unit includes a first switch connected to a ground terminal and a second switch connected to an input node of the first integrating circuit unit,
the first switch and the second switch are turned on and turned off at a predetermined interval, and
the interval at which the first switch and the second switch are turned on and turned off is equal to half of a period for which the driving signal is applied to the first capacitor.
4. The capacitance sensing apparatus of claim 3 , wherein the second integrating circuit unit includes a third switch connected to a ground terminal and a fourth switch connected to an input node of the second integrating circuit unit,
the third and fourth switches are turned on and turned off at a predetermined interval, and
the interval at which the third and fourth switches are turned on and turned off is equal to a period for which the driving signal is applied to the first capacitor.
5. The capacitance sensing apparatus of claim 4 , wherein the third and fourth switches are turned on and turned off so as to have a phase difference from the period for which the driving signal is applied to the first capacitor by a period equal to a time for which the first or second switch is turned on.
6. The capacitance sensing apparatus of claim 3 , wherein the first integrating circuit unit further includes a fifth switch resetting the second capacitor, the fifth switch being operated in the same manner as that of the first switch.
7. A capacitance sensing method comprising:
applying a driving signal to a first capacitor;
charging and discharging a second capacitor twice during a single period in which the first capacitor is charged and discharged to generate a first output voltage; and
charging a third capacitor with charges from the second capacitor to generate a second output voltage,
changes in a level of the second output voltage being detected multiple times during the single period in which the first capacitor is charged and discharged, wherein a level of the first output voltage is repeatedly: decreased, held, increased, held, increased, held, decreased, and held consecutively.
8. The capacitance sensing method of claim 7 , wherein in the generating of the first output voltage, a first switch connected to a ground terminal and a second switch connected to an input node of a first integrating circuit unit generating the first output voltage are turned on and turned off twice during the single period in which the first capacitor is charged and discharged.
9. The capacitance sensing method of claim 8 , wherein in the generating of the second output voltage, a third switch connected to a ground terminal and a fourth switch connected to an input node of a second integrating circuit unit generating the second output voltage are turned on and turned off once during the single period in which the first capacitor is charged and discharged.
10. The capacitance sensing method of claim 9 , wherein in the generating of the second output voltage, the third switch and the fourth switch are turned on and turned off so as to have a phase difference from a period for which the driving signal is applied to the first capacitor by a period equal to a time for which the first or second switch is turned on.
11. A touch screen apparatus comprising:
a panel unit including a plurality of driving electrodes and a plurality of sensing electrodes;
a driving circuit unit applying a driving signal to each of the plurality of driving electrodes;
a sensing circuit unit sensing changes in capacitance generated in intersections between the driving electrodes to which the driving signal is applied and the plurality of sensing electrodes; and
a controlling unit controlling operations of the driving circuit unit and the sensing circuit unit,
the sensing circuit unit including a first integrating unit and a second integrating circuit unit, and
a level of an output signal from the second integrating circuit unit being changed multiple times during a single period of the driving signal, and
a capacitor included in the first integrating circuit unit being charged and discharged twice during a single period of the driving signal, wherein a level of an output signal from the first integrating circuit unit is repeatedly: decreased, held, increased, held, increased, held, decreased, and held consecutively.
12. The touch screen apparatus of claim 11 , wherein the second integrating circuit unit generates the output signal transferred to the controlling unit based on charges charged in a capacitor included in the first integrating circuit unit.
13. The touch screen apparatus of claim 12 , wherein the controlling unit determines a touch input applied to the panel unit based on the output signal from the second integrating circuit unit.
14. The touch screen apparatus of claim 11 , wherein the level of the output signal from the second integrating circuit unit is increased when a level of an output signal from the first integrating circuit unit is decreased.
15. The capacitance sensing apparatus of claim 3 , wherein the interval at which the first switch and the second switch are turned on and turned off, which is equal to half of the period for which the driving signal is applied to the first capacitor, causes the second capacitor to be charged and discharged twice during the single period during which the first capacitor is charged and discharged once by the driving circuit.
16. The capacitance sensing apparatus of claim 3 , wherein the interval at which the first switch and second switch are turned on and off, which is equal to half of the period for which the driving signal is applied the first capacitor, causes one or more of the first integrating circuit unit and the second integrating circuit unit to perform integration twice in positive and negative directions during the period for which the driving signal is applied to the first capacitor.