TOUCH SENSING SYSTEM AND METHOD FOR DRIVING THE SAME

• US 20140139480A1
• Filed: 11/14/2013
• Published: 05/22/2014
• Est. Priority Date: 11/16/2012
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Seo, Sangwoo, Lee, Jaedo, JEONG, Beom, Choi, Sungpil
• Granted Patent: US 9,766,755 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/04164 Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

A touch sensing system and a method for driving the same are disclosed. The touch sensing system includes a touch screen including touch sensors and a touch sensing circuit applying a driving signal to the touch sensors. The touch sensing circuit applies at least one first driving signal to a first position of the touch screen and applies at least one second driving signal to a second position of the touch screen. When RC delay of the first position is less than RC delay of the second position, at least one of a width and a voltage of the second driving signal is greater than the first driving signal, or the number of second driving signals is more than the number of first driving signals.

Claims

1. A touch sensing system comprising:

a touch screen including touch sensors; and

a touch sensing circuit configured to apply a driving signal to the touch sensors,

wherein the touch sensing circuit applies at least one first driving signal to a first position of the touch screen and applies at least one second driving signal to a second position of the touch screen,

wherein when RC delay of the first position is less than RC delay of the second position, at least one of a width and a voltage of the second driving signal is greater than the first driving signal, or the number of second driving signals is more than the number of first driving signals.

2. The touch sensing system of claim 1, wherein at least one of the width and the voltage of each of the first and second driving signals increases in proportion to the RC delay, or the number of first driving signals and the number of second driving signals increase in proportion to the RC delay.

3. The touch sensing system of claim 1, wherein the touch screen is divided into a plurality of blocks,

wherein each of the plurality of blocks includes at least two lines to which the driving signal is applied,

wherein the widths, the voltages, and the number of the driving signals applied to one block are the same,

wherein at least one of the width and the voltage of the driving signal applied to a block having the relatively large RC delay among the plurality of blocks is greater than the driving signal applied to a block having the relatively small RC delay, or the number of driving signals applied to a block having the relatively large RC delay among the plurality of blocks is more than the number of driving signals applied to a block having the relatively small RC delay.

4. The touch sensing system of claim 1, wherein the driving signal includes a pre-charging period during which a first voltage is applied to the touch sensors, and a high potential holding period during which a second voltage less than the first voltage is applied to the touch sensors,

wherein the pre-charging period is set to be earlier than the high potential holding period.

5. The touch sensing system of claim 4, wherein the driving signal further includes a discharge acceleration period during which a third voltage less than the second voltage is applied to the touch sensors, and a reference potential period during which a reference voltage, which is less than the second voltage and greater than the third voltage, is applied to the touch sensors,

wherein the discharge acceleration period is set to be arranged between the high potential holding period and the reference potential period.

6. The touch sensing system of claim 5, wherein the driving signal is generated in one waveform of a sine wave, a triangle wave, and a sawtooth wave.

7. The touch sensing system of claim 6, wherein the touch screen is divided into a plurality of blocks,

wherein each of the plurality of blocks includes at least two lines to which the driving signal is applied,

wherein the first and third voltages applied to one block are equal to each other,

wherein the first and third voltages applied to one block of the plurality of blocks are set to be different from the first and third voltages applied to other blocks.

8. The touch sensing system of claim 7, wherein the first and third voltages are proportional to the RC delay of the touch screen.

9. The touch sensing system of claim 8, wherein the first and third voltages of the driving signal applied to a first block positioned closest to the touch sensing circuit are set to be less than the first and third voltages applied to other blocks or are set to a minimum value.

10. The touch sensing system of claim 9, wherein the first and third voltages of the driving signal applied to a third block positioned farthest away from the touch sensing circuit are greater than the first and third voltages applied to other blocks,

wherein the first and third voltages of the driving signal applied to a second block positioned between the first block and the third block are greater than the first and third voltages of the driving signal applied to the first block and are less than the first and third voltages of the driving signal applied to the third block.

11. A method for driving a touch sensing system including a touch screen including touch sensors and a touch sensing circuit applying a driving signal to the touch sensors, the method comprising:

applying at least one first driving signal to a first position of the touch screen; and

applying at least one second driving signal to a second position of the touch screen

wherein when RC delay of the first position is less than RC delay of the second position, at least one of a width and a voltage of the second driving signal is greater than the first driving signal, or the number of second driving signals is more than the number of first driving signals.

12. The method of claim 11, wherein at least one of the width and the voltage of each of the first and second driving signals increases in proportion to the RC delay, or the number of first driving signals and the number of second driving signals increase in proportion to the RC delay.

13. The method of claim 11, wherein the touch screen is divided into a plurality of blocks,

wherein each of the plurality of blocks includes at least two lines to which the driving signal is applied.

wherein the widths, the voltages, and the number of the driving signals applied to one block are the same,

wherein at least one of the width and the voltage of the driving signal applied to a block having the relatively large RC delay among the plurality of blocks is greater than the driving signal applied to a block having the relatively small RC delay, or the number of driving signals applied to a block having the relatively large RC delay among the plurality of blocks is more than the number of driving signals applied to a block having the relatively small RC delay.

14. The method of claim 13, wherein the driving signal includes a pre-charging period during which a first voltage is applied to the touch sensors, and a high potential holding period during which a second voltage less than the first voltage is applied to the touch sensors,

wherein the pre-charging period is set to be earlier than the high potential holding period.

15. The method of claim 14, wherein the driving signal further includes a discharge acceleration period during which a third voltage less than the second voltage is applied to the touch sensors, and a reference potential period during which a reference voltage, which is less than the second voltage and greater than the third voltage, is applied to the touch sensors,

wherein the discharge acceleration period is set to be arranged between the high potential holding period and the reference potential period.

16. The method of claim 15, wherein the touch screen is divided into a plurality of blocks,

wherein each of the plurality of blocks includes at least two lines to which the driving signal is applied,

wherein the first and third voltages applied to one block are equal to each other,

wherein the first and third voltages applied to one block of the plurality of blocks are set to be different from the first and third voltages applied to other blocks.

17. The method of claim 16, wherein the first and third voltages are proportional to the RC delay of the touch screen.

18. The method of claim 17, wherein the first and third voltages of the driving signal applied to a first block positioned closest to the touch sensing circuit are set to be less than the first and third voltages applied to other blocks or are set to a minimum value.

19. The method of claim 18, wherein the first and third voltages of the driving signal applied to a third block positioned farthest away from the touch sensing circuit are greater than the first and third voltages applied to other blocks,

wherein the first and third voltages of the driving signal applied to a second block positioned between the first block and the third block are greater than the first and third voltages of the driving signal applied to the first block and are less than the first and third voltages of the driving signal applied to the third block.