SIGNAL PROCESSING CIRCUIT OF TOUCH SCREEN

• US 20140247241A1
• Filed: 03/14/2013
• Published: 09/04/2014
• Est. Priority Date: 03/04/2013
• Status: Active Grant

• Current Assignee: DB Globalchip Company Limited
• Original Assignee: Dongbu HiTek Co., Ltd. (DB HiTek Co., Ltd.)
• Inventors: HEO, Woon Hyung
• Granted Patent: US 9,116,588 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• 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 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
• CPC Class Codes: G06F 3/0488 using a touch-screen or digitiser, e.g. input of commands through traced gestures

Abstract

A signal processing circuit of a touch screen is provided. The signal processing circuit can include driving and sensing lines arranged to interact with one another in a touch screen panel, power sources supplying power to each of the driving lines, and sensing channels detecting touch by sensing a mutual capacitance on a node where the sensing line interacts with the driving line. The circuit can also include driving line switches selectively connecting the power sources to the driving lines, channel switches selectively connecting the sensing channels to the sensing lines, and a bypass line allowing the driving line to be connected to the sensing line by operation of the channel switches.

Claims

1. A signal processing circuit of a touch screen, comprising:

a plurality of driving lines and a plurality of sensing lines arranged to interact with one another in a touch screen panel;

power sources respectively supplying power to each of the driving lines;

sensing channels respectively connected to the sensing lines, wherein each sensing channel is configured to detect a touch by sensing a mutual capacitance on a node where the respective sensing line interacts with a driving line of the plurality of driving lines;

a driving line switch for each driving line, selectively connecting the respective power source to the driving line;

a channel switch for each sensing channel, selectively connecting the respective sensing channel to the sensing line; and

a bypass line configured to connect a driving line of the plurality of driving lines to a sensing line of the plurality of sensing lines by operation of the respective channel switch.

2. The signal processing circuit according to claim 1, wherein the bypass line is also configured to connect a driving line of the plurality of driving lines to a sensing line of the plurality of sensing lines by operation of the respective driving line switch.

3. The signal processing circuit according to claim 1, wherein the bypass line is configured such that, when the channel switch is connecting its respective sensing channel to the respective sensing line one end of the bypass line is open.

4. The signal processing circuit according to claim 3, wherein the signal processing unit is configured such that, if the driving line switches are open such that each power source is disconnected from its respective driving line, and the bypass line is connected to the sensing channel by an operation of the respective channel switch, the sensing channel then uses a noise voltage as an input voltage.

5. The signal processing circuit according to claim 4, further comprising a distortion detecting unit configured to determine whether noise is present based on a voltage readout of the sensing channels.

6. The signal processing circuit according to claim 5, wherein the distortion detecting unit is formed as an analog circuit including a comparator or is implemented as firmware.

7. The signal processing circuit according to claim 1, wherein the signal processing unit is configured such that, if the driving lines switch open such that each power source is disconnected from its respective driving line, and the bypass line is connected to the sensing channel by an operation of the respective channel switch, the sensing channel then uses a noise voltage as an input voltage.

8. The signal processing circuit according to claim 1, comprising a plurality of bypass lines, one for each driving line.

9. The signal processing circuit according to claim 8, comprising an equal number of driving lines and sensing lines.

10. The signal processing circuit according to claim 8, wherein each bypass line is configured such that, when the channel switch is connecting its respective sensing channel to the respective sensing line, one end of the bypass line is open.

11. The signal processing circuit according to claim 10, wherein the signal processing unit is configured such that, if the driving line switches are open such that each power source is disconnected from its respective driving line, and each bypass line is connected to its respective sensing channel by an operation of the respective channel switch, the sensing channels then use a noise voltage as an input voltage.

12. The signal processing circuit according to claim 11, further comprising a distortion detecting unit configured to determine whether noise is present based on a voltage readout of the sensing channels.

13. A method of detecting a touch of a touch screen, the method comprising:

providing a signal processing circuit of the touch screen, the signal processing circuit comprising;

a plurality of driving lines and a plurality of sensing lines arranged to interact with one another in a touch screen panel;

power sources respectively supplying power to each of the driving lines;

sensing channels respectively connected to the sensing lines, wherein each sensing channel is configured to detect a touch by sensing a mutual capacitance on a node where the respective sensing line interacts with a driving line of the plurality of driving lines;

a driving line switch for each driving line, selectively connecting the respective power source to the driving line;

a channel switch for each sensing channel, selectively connecting the respective sensing channel to the sensing line;

a bypass line configured to connect a driving line of the plurality of driving lines to a sensing line of the plurality of sensing lines by operation of the respective channel switch; and

a distortion detecting unit configured to determine whether noise is present based on a voltage readout by the sensing channels;

determining whether noise is present based on a voltage readout by the sensing channels; and

if a noise voltage is present, opening the driving line switches such that each power source is disconnected from its respective driving line, and connecting the bypass line to the sensing channel by an operation of the respective channel switch, such that the sensing channel uses the noise voltage as an input voltage;

if a noise voltage is not present, connecting each sensing channel to its respective sensing line, such that one end of the bypass line is open and each sensing channels use the power sources as an input voltage.

14. The method according to claim 13, wherein the distortion detecting unit is formed as an analog circuit including a comparator or is implemented as firmware.

15. The method according to claim 13, wherein the signal processing circuit comprises a plurality of bypass lines, one for each driving line.

16. The signal processing circuit according to claim 15, wherein the signal processing circuit comprises an equal number of driving lines and sensing lines.

17. The method according to claim 15, wherein each bypass line is configured such that, when the channel switch is connecting its respective sensing channel to the respective sensing line, one end of the bypass line is open.

18. The method according to claim 15, if a noise voltage is present, each bypass line is connected to a sensing channel by an operation of the respective channel switch.