In-cell capacitive touch screen and touch contact detecting method and system thereof

1. A method for detecting a touch contact on an in-cell capacitive touch screen, the method comprising:

based on different gray scale pictures displayed by the in-cell capacitive touch screen in a non-touch state and a distribution of intersections of rows and columns of the in-cell capacitive touch screen, obtaining noise values corresponding to different gray scales for each of the intersections in the non-touch state;

based on a current picture displayed by the in-cell capacitive touch screen and the obtained noise values corresponding to the different gray scales for each intersection in the non-touch state, obtaining a theoretical noise value for each intersection under a condition of the current picture; and

for each of the intersections of the rows and the columns of the in-cell capacitive touch screen, compensating a detected signal at each intersection with the theoretical noise value for the intersection under the condition of the current picture to locate a position of the touch contact;

wherein the theoretical noise value for each intersection is calculated by an equation:

N=N 0 +Σ 1 J N m /(1 +X m /X )+Σ 1 K N n /(1 +Y n /Y )

where N denotes the theoretical noise value corresponding to the current gray scale for the calculated intersection; No denotes the noise value corresponding to the current gray scale for the calculated intersection in the non-touch state; X denotes the length in the row direction of a picture block of the current gray scale displayed at the calculated intersection in the current display picture; Y denotes the length in the column direction of the picture block of the current gray scale displayed at the calculated intersection in the current display picture; J represents a total number of intersections which has an impact on and is in the same row with the calculated intersection; K represents a total number of intersections which has an impact on and is in the same column with the calculated intersection; X m denotes the distance between the calculated intersection and an m-th impacting intersection in the same row with the calculated intersection; N m denotes the noise value corresponding to the current gray scale for the m-th impacting intersection in the non-touch state; Y n denotes the distance between the calculated intersection and an n-th impacting intersection in the same column with the calculated intersection; and N n denotes the noise value corresponding to the current gray scale for the n-th impacting intersection in the non-touch state.

2. The method according to claim 1 , wherein detected signals present when the in-cell capacitive touch screen displays respective gray scale pictures are measured or simulated for obtaining the noise values corresponding to the different gray scale pictures for each intersection in the non-touch state.

3. The method according to claim 1 , wherein, in the non-touch state, the number of the different gray scale pictures displayed by the in-cell capacitive touch screen is 256, and each of the different gray scale pictures has a gray scale which is one of the gray scales in a range of 0-255; or the number of the different gray scale pictures displayed by the in-cell capacitive touch screen is 32, and each of the different gray scale pictures has a gray scale which is one of the gray scales in a range of 0-31; or the number of the different gray scale pictures displayed by the in-cell capacitive touch screen is 64, and each of the different gray scale pictures has a gray scale which is one of the gray scales in a range of 0-63; or the number of the different gray scale pictures displayed by the in-cell capacitive touch screen is 128, and each of the different gray scale pictures has a gray scale which is one of the gray scales in a range of 0-127; or the number of the different gray scale pictures displayed by the in-cell capacitive touch screen is 16, and each of the different gray scale pictures has a gray scale which is one of the gray scales in a range of 0-15.

4. The method according to claim 1 , wherein the obtained noise values corresponding to the different gray scales for each intersection in the non-touch state form a table.

5. The method according to claim 1 , wherein obtaining a theoretical noise value for each intersection under the condition of the current picture comprises:

determining a current gray scale at each intersection, based on the current picture displayed by the in-cell capacitive touch screen;

determining a noise value corresponding to the current gray scale for each intersection in the non-touch state based on the noise values corresponding to the different gray scales for each intersection in the non-touch state; and

calculating the theoretical noise value for each intersection under the condition of the current picture based on the noise value corresponding to the current gray scale for an intersection in the non-touch state and the noise values corresponding to the current gray scale for other intersections in the non-touch state which are in a same row and/or column with said intersection.

6. The method according to claim 1 , wherein J and K each are no less than 2.

7. The method according to claim 1 , wherein J and K are set based on the display resolution of the in-cell capacitive touch screen.

8. A system for detecting a touch contact on an in-cell capacitive touch screen, the system comprising:

a storage module configured to store noise values corresponding to different gray scales for each intersection of rows and columns of the in-cell capacitive touch screen in a non-touch state;

a theoretical noise calculation module configured to obtain a theoretical noise value for each intersection under a condition of a current picture based on the current picture displayed by the in-cell capacitive touch screen and the noise values corresponding to the different gray scales for each intersection in the non-touch state; and

a touch contact detection module configured to obtain a detected signal at each intersection and compensate the detected signal at each intersection with the theoretical noise value for each intersection under the condition of the current picture to locate a position of the touch contact;

wherein the theoretical noise value for each intersection is calculated by an equation:

N=N 0 +Σ 1 J N m /(1 +X m /X )+Σ 1 K N n /(1 +Y n /Y )

where N denotes the theoretical noise value corresponding to the current gray scale for the calculated intersection; N 0 denotes the noise value corresponding to the current gray scale for the calculated intersection in the non-touch state; X denotes the length in the row direction of a picture block of the current gray scale displayed at the calculated intersection in the current display picture; Y denotes the length in the column direction of the picture block of the current gray scale displayed at the calculated intersection in the current display picture; J represents a total number of intersections which has an impact on and is in the same row with the calculated intersection; K represents a total number of intersections which has an impact on and is in the same column with the calculated intersection; X m denotes the distance between the calculated intersection and an m-th impacting intersection in the same row with the calculated intersection; N m denotes the noise value corresponding to the current gray scale for the m-th impacting intersection in the non-touch state; Y n denotes the distance between the calculated intersection and an n-th impacting intersection in the same column with the calculated intersection; and N m denotes the noise value corresponding to the current gray scale for the n-th impacting intersection in the non-touch state.

9. The system of claim 8 , wherein, in the non-touch state, the number of the different gray scale pictures displayed by the in-cell capacitive touch screen is 256, and each of the different gray scale pictures has a gray scale which is one of the gray scales in a range of 0-255; or the number of the different gray scale pictures displayed by the in-cell capacitive touch screen is 32, and each of the different gray scale pictures has a gray scale which is one of the gray scales in a range of 0-31; or the number of the different gray scale pictures displayed by the in-cell capacitive touch screen is 64, and each of the different gray scale pictures has a gray scale which is one of the gray scales in a range of 0-63; or the number of the different gray scale pictures displayed by the in-cell capacitive touch screen is 128, and each of the different gray scale pictures has a gray scale which is one of the gray scales 0-127 in a range of; or the number of the different gray scale pictures displayed by the in-cell capacitive touch screen is 16, and each of the different gray scale pictures has a gray scale which is one of the gray scales in a range of 0-15.

10. The system according to claim 8 , wherein the noise values corresponding to the different gray scales for each intersection in the non-touch state are stored as a table by the storage module.

11. The system according to claim 8 , wherein obtaining the theoretical noise value for each intersection under the condition of the current picture by the theoretical noise calculation module comprises:

Determining a current gray scale at each intersection based on the current picture displayed by the in-cell capacitive touch screen;

determining a noise value corresponding to the current gray scale for each intersection in the non-touch state based on the noise values corresponding to the different gray scales for each intersection in the non-touch state which are stored in the storage module; and

calculating the theoretical noise value for each intersection under the condition of the current picture based on the noise value corresponding to a current gray scale for an intersection in the non-touch state and the noise values corresponding to the current gray scale for other intersections in the non-touch state which are in a same row and/or column with said intersection.

12. The system according to claim 8 , wherein J and K each are no less than 2.

13. The system according to claim 8 , wherein J and K are set based on the display resolution of the in-cell capacitive touch screen.

14. An in-cell capacitive touch screen including a system for detecting the touch contact on the in-cell capacitive touch screen, the system comprising:

a storage module configured to store noise values corresponding to different gray scales for each intersection of rows and columns of the in-cell capacitive touch screen in a non-touch state;

a theoretical noise calculation module configured to obtain a theoretical noise value for each intersection under a condition of a current picture based on the current picture displayed by the in-cell capacitive touch screen and the noise values corresponding to the different gray scales for each intersection in the non-touch state; and

a touch contact detection module configured to obtain a detected signal at each intersection and compensate the detected signal at each intersection with the theoretical noise value for each intersection under the condition of the current picture to locate a position of the touch contact;

wherein the theoretical noise value for each intersection is calculated by an equation:

N=N 0 +Σ 1 J N m /(1 +X m /X )+Σ 1 K N n /(1 +Y n /Y )

where N denotes the theoretical noise value corresponding to the current gray scale for the calculated intersection; N 0 denotes the noise value corresponding to the current gray scale for the calculated intersection in the non-touch state; X denotes the length in the row direction of a picture block of the current gray scale displayed at the calculated intersection in the current display picture; Y denotes the length in the column direction of the picture block of the current gray scale displayed at the calculated intersection in the current display picture; J represents a total number of intersections which has an impact on and is in the same row with the calculated intersection; K represents a total number of intersections which has an impact on and is in the same column with the calculated intersection; X m denotes the distance between the calculated intersection and an m-th impacting intersection in the same row with the calculated intersection; N m denotes the noise value corresponding to the current gray scale for the m-th impacting intersection in the non-touch state; Y n denotes the distance between the calculated intersection and an n-th impacting intersection in the same column with the calculated intersection; and N n denotes the noise value corresponding to the current gray scale for the n-th impacting intersection in the non-touch state.