Touch sensing device and method for driving the same
A touch sensing device includes a touch screen coupled with a display panel including data lines, gate lines crossing the data lines, and pixels arranged in a matrix form, and a touch sensing circuit which supplies a driving signal to lines of the touch screen and senses a touch input. The touch sensing circuit detects an optimum sensing time, in which changes in a voltage change of the gate lines are maintained within a previously determined allowable range, in a touch screen drive period in which data is not written to the pixels of the display panel. The touch sensing circuit supplies the driving signal to the lines of the touch screen only in the optimum sensing time of the touch screen drive period.
1. A touch sensing display device comprising:
a touch screen integrated with a display panel including data lines, gate lines crossing the data lines, touch electrodes for sensing a touch input, and pixels at crossings of the gate lines and the data lines, the gate lines separate and disconnected from the touch electrodes; and
a touch sensing circuit configured to operate according to a control signal, the control signal including a first level for a first period and a second level for a second period, wherein:
a common voltage is supplied to all the touch electrodes to display an image on the pixels during the first period of the control signal in which the control signal is at the first level;
the touch sensing circuit does not supply a touch driving signal to any of the touch electrodes during a first part of the second period of the control signal in which the control signal is at the second level, and a voltage at the gate lines is changed from a first voltage to a second voltage during the first part of the second period of the control signal in which the control signal is at the second level, the first part of the second period of the control signal following the first period of the control signal; and
the touch sensing circuit supplies the touch driving signal to one or more of the touch electrodes during a second part of the second period of the control signal in which the control signal is at the second level, the second part of the second period of the control signal being subsequent to the first part of the second period of the control signal, touch sensing signals from the one or more touch electrodes responsive to the touch drive signal being used to detect the touch input.
2. The touch sensing display device of claim 1 , further comprising a display panel driving circuit configured to write data to the pixels of the display panel during the first period of the control signal and to not write data to the pixels of the display panel during the second period of the control signal.
3. The touch sensing display device of claim 1 , wherein the touch sensing circuit does not supply the touch driving signal to any of the touch electrodes during a third part of the second period of the control signal in which the control signal is at the second level, the third part of the second period of the control signal being subsequent to the second part of the second period of the control signal and preceding another first period of the control signal of a subsequent frame, and the voltage at the gate lines is changed from the second voltage to the first voltage during the third part of the second period of the control signal in which the control signal is at the second level.
4. The touch sensing display device of claim 3 , wherein a ripple of the voltage measured at the gate lines during the second part of the second period of the control signal is less than the ripple of the voltage measured at the gate lines during the first part or the third part of the second period of the control signal.
5. A method for driving a touch sensing display device including a touch screen integrated with a display panel including data lines, gate lines crossing the data lines, touch electrodes for sensing a touch input, and pixels at crossings of the gate lines and the data lines, the gate lines separate and disconnected from the touch electrodes, the touch sensing display device operated according to a control signal, the control signal including a first level for a first period and a second level for a second period, the method comprising:
supplying a common voltage to all the touch electrodes to display an image on the pixels during the first period of the control signal in which the control signal is at the first level;
not supplying a touch driving signal to any of the touch electrodes during a first part of the second period of the control signal in which the control signal is at the second level, the first part of the second period of the control signal following the first period of the control signal and a voltage at the gate lines being changed from a first voltage to a second voltage during the first part of the second period of the control signal in which the control signal is at the second level; and
supplying the touch driving signal to one or more of the touch electrodes during a second part of the second period of the control signal in which the control signal is at the second level, the second part of the second period of the control signal being subsequent to the first part of the second period of the control signal, touch sensing signals from the one or more touch electrodes responsive to the touch drive signal being used to detect the touch input.
6. The method of claim 5 , further comprising:
not supplying the touch driving signal to any of the touch electrodes during a third part of the second period of the control signal in which the control signal is at the second level, the third part of the second period of the control signal being subsequent to the second part of the second period of the control signal and preceding another first period of the control signal of a subsequent frame, and the voltage at the gate lines being changed from the second voltage to the first voltage during the third part of the second period of the control signal in which the control signal is at the second level.
7. The method of claim 6 , wherein a ripple of the voltage measured at the gate lines during the second part of the second period of the control signal is less than the ripple of the voltage measured at the gate lines during the first part or the third part of the second period of the control signal.
8. The method of claim 5 ,
wherein data is written to the pixels of the display panel during the first period of the control signal, and
wherein data is not written to the pixels of the display panel during the second period of the control signal.
9. A driver circuit for driving a touch sensing display device including a touch screen integrated with a display panel including data lines, gate lines crossing the data lines, touch electrodes for sensing a touch input, and pixels at crossings of the gate lines and the data lines, the gate lines separate and disconnected from the touch electrodes, the touch sensing display device operated according to a control signal, the control signal including a first level for a first period and a second level for a second period,
the driver circuit comprising circuitry to supply a common voltage or a touch driving signal, wherein:
the circuitry supplies the common voltage to all the touch electrodes to display an image on the pixels during the first period of the control signal in which the control signal is at the first level;
the circuitry does not supply the touch driving signal to any of the touch electrodes during a first part of the second period of the control signal in which the control signal is at the second level, the first part of the second period of the control signal following the first period of the control signal, and a voltage at the gate lines being changed from a first voltage to a second voltage during the first part of the second period of the control signal in which the control signal is at the second level; and
the circuitry supplies the touch driving signal to one or more of the touch electrodes during a second part of the second period of the control signal in which the control signal is at the second level, the second part of the second period of the control signal being subsequent to the first part of the second period of the control signal, touch sensing signals from the one or more touch electrodes responsive to the touch drive signal being used to detect the touch input.
10. The driver circuit of claim 9 ,
wherein the circuitry does not supply the touch driving signal to any of the touch electrodes during a third part of the second period of the control signal in which the control signal is at the second level, the third part of the second period of the control signal being subsequent to the second part of the second period of the control signal and preceding another first period of the control signal of a subsequent frame, and the voltage at the gate lines being changed from the second voltage to the first voltage during the third part of the second period of the control signal in which the control signal is at the second level.
11. The driver circuit of claim 10 , wherein a ripple of the voltage measured at the gate lines during the second part of the second period of the control signal is less than the ripple of the voltage measured at the gate lines during the first part or the third part of the second period of the control signal.
12. The driver circuit of claim 9 ,
wherein data is written to the pixels of the display panel during the first period of the control signal, and
wherein data is not written to the pixels of the display panel during the second period of the control signal.
13. The display device of claim 1 , wherein the touch sensing circuit is configured to operate in a display mode or a touch mode depending on the control signal, wherein the first level of the control signal is indicative of the display mode and the second level of the control signal is indicative of the touch mode.
14. The display device of claim 1 , wherein the first part of the second period of the control signal immediately follows the first period of the control signal.
15. The display device of claim 1 , wherein the touch sensing circuit generates a counter value and determines timing of the second part of the second period of the control signal based on the counter value.
16. The display device of claim 1 , wherein the touch sensing circuit determines timing of the second part of the second period of the control signal based on the voltage at the gate lines.
17. The display device of claim 16 , wherein the touch sensing circuit determines timing of the second part of the second period of the control signal based on a comparison of the voltage at the gate lines to a reference.
18. The driver circuit of claim 9 , wherein the circuitry generates a counter value and determines timing of the second part of the second period of the control signal based on the counter value.
19. The driver circuit of claim 9 , wherein the circuitry determines timing of the second part of the second period of the control signal based on the voltage at the gate lines.
20. The driver circuit of claim 19 , wherein the circuitry determines timing of the second part of the second period of the control signal based on a comparison of the voltage at the gate lines to a reference.