TOUCHSCREEN AND DRIVING METHOD THEREOF

• US 20110122079A1
• Filed: 11/19/2010
• Published: 05/26/2011
• Est. Priority Date: 11/24/2009
• Status: Abandoned Application

• Current Assignee: InnoLux Corporation
• Original Assignee: Chi Mei Innolux Corporation (InnoLux Corporation)
• Inventors: CHAO, CHIH-HAN, SHIH, PO-SHENG, CHEN, PO-YANG
• Application Number:
  US12/949,805
• Publication Number:
  US 20110122079A1
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

A touchscreen includes a touch panel including a plurality of sensor electrodes, a drive circuit including a plurality of the first transistors respectively corresponding to the sensor electrodes. The drive circuit is configured for detecting voltage on the sensor electrodes. When the touchscreen is initializing, a first voltage is provided to pre-charge the sensor electrodes, and a second voltage is provided to further charge the sensor electrodes via each first transistor. In addition, the first voltage and a voltage difference formed between the first and the second voltage are both less than or about equal to the source-drain withstanding voltage of each first transistor.

Claims

1. A touchscreen, comprising:

a touch panel comprising a plurality of sensor electrodes for sensing a contact position on the touch panel;

a drive circuit comprising a plurality of first transistors respectively corresponding to the sensor electrodes, and configured for detecting voltage on the sensor electrodes;

wherein when the touchscreen is initializing, a first voltage is provided to pre-charge the sensor electrodes, and a second voltage is provided to further charge the sensor electrodes via each first transistor, the first voltage and a voltage difference formed between the first and the second voltage are both less than or about equal to a source-drain withstanding voltage of each first transistor.

2. The touchscreen of claim 1, wherein the drive circuit further comprising an auxiliary circuit for providing the first voltage to the sensor electrodes.

3. The touchscreen of claim 2, wherein the auxiliary circuit comprises a third transistor, and the first voltage, the voltage difference are both less than or about equal to the source-drain withstanding voltage of the third transistor.

4. The touchscreen of claim 2, wherein the drive circuit comprises a plurality of the detection units and a processing circuit respectively connecting with the detection units, wherein the detection units each comprises a first transistor corresponding to a sensor electrode, and configured for detecting the voltage on the corresponding sensor electrode, wherein the processing circuit is configured for confirming the contact position according to voltage output by the detection units.

5. The touchscreen of claim 4, wherein each detection unit further comprises a second transistor, the voltage of each sensor electrode are read by the processing circuit via a corresponding second transistor.

6. The touchscreen of claim 5, wherein each detection unit further comprises a step-down circuit, when the touchscreen is operating, the voltage of each sensor electrode are output to the second transistors via the step-down circuits, and voltage output by the step-down circuits are less than or about equal to the source-drain withstanding voltage of the second transistors.

7. The touchscreen of claim 6, wherein each step-down circuit comprises a first resistor and a second resistor connected in series with the first resistor, one end of the first resistor connecting with the second resistor is connected to the second transistor, the other end of the first resistor is connected to the sensor electrode, one end of the second resistor is connected to the first resistor, and the other end of the second resistor is connected to the ground.

8. The touchscreen of claim 7, wherein the drive circuit further comprises a time schedule controller, when the touchscreen is initializing, the time schedule controller controls the third transistor to be switched on, and the first and the second transistors to be switched off, accordingly, the first voltage is provided to pre-charge the sensor electrodes via the third transistor, when the voltage of the sensor electrodes are about equal to the first voltage, the time schedule controller controls the third transistor to be switched off and the first transistors to be switched on, accordingly, the second voltage is provided to charge the sensor electrodes again via the first transistors, and when the voltage of the sensor electrode are about equal to the second voltage, the touchscreen begins operation.

9. The touchscreen of claim 8, wherein the first voltage is provided by a first external power supply, the second voltage is provided by a second external power supply, and the drive circuit further comprises a first capacitor connected in parallel with the first external power supply, a second capacitor connected in parallel with the second external power supply, when the touchscreen stops working, the time schedule controller controls the first and the second transistors to be switched off, and the third transistor to be switched on, accordingly, the sensor electrodes discharge via the third transistor.

10. The touchscreen of claim 9, wherein the touch panel further comprises a first substrate, a second substrate opposite to the first substrate, and a first conductive coating comprising a first transparent conductive layer, a second conductive coating comprising a second transparent conductive layer and a plurality of sensor electrodes disposed on the second transparent conductive layer along a first axis, the first and the second conductive coatings disposed on inner surfaces of the first and the second substrates respectively, wherein the second conductive coating is made from a carbon nanotube film comprising a plurality of carbon nanotubes arranged along the first axis, with extension of the axis of each carbon nanotube parallel with a second axis perpendicular to the first axis.

11. The touchscreen of claim 10, wherein the processing circuit comprises an analog-digital converter for converting an analog voltage output by each step-down circuit into a digital voltage and a microcontroller connected with the analog-digital converter for comparing the digital voltage output by the analog-digital converter to acquire coordinates of the contact position.

12. The touchscreen of claim 11, wherein the processing circuit further comprises a buffer connected between the analog-digital converter and the microcontroller for storing the digital voltage output by the analog-digital converter and outputting the digital voltage to the microcontroller when the microcontroller reads the digital voltage.

13. A method for driving a touchscreen, the touchscreen comprising a touch panel and a drive circuit, the touch panel comprising a plurality of sensor electrodes, the drive circuit comprising a plurality of the first transistors respectively corresponding to the sensor electrodes, the method for driving the touchscreen to initialize comprising:

providing a first voltage to pre-charge the sensor electrodes; and

providing a second voltage to further charge the sensor electrodes via each first transistor;

wherein the first voltage, a voltage difference formed between the first and the second voltage are both less than or about equal to the source-drain withstanding voltage of the first transistors.

14. The method of claim 13, wherein the drive circuit further comprises an auxiliary circuit, the first voltage is provided to pre-charge the sensor electrodes via the auxiliary circuit.

15. The method of claim 14, wherein the auxiliary circuit comprises a third transistor, the first voltage and the voltage difference are both less than or about equal to the source-drain withstanding voltage of the third transistor.

16. The method of claim 15, further comprising:

scanning the sensor electrodes and outputting scan voltage corresponding to the voltage on the sensor electrodes;

confirming a contact position on the touch panel according to the scan voltage.

17. The method of claim 16, wherein the drive circuit further comprises a plurality of detection units and a processing circuit connected to the detection units, each detection unit is connected to a corresponding sensor electrode, wherein the detection units are configured for scanning the sensor electrodes and outputting scan voltage corresponding to the voltage on the sensor electrodes, and the processing circuit is configured for confirming a contact position on the touch panel according to the scan voltage output by the detection units.

18. The method of claim 17, wherein each detection unit comprises a second transistor, the voltage of the sensor electrodes are provided to the processing circuit via each second transistor.

19. The method of claim 18, wherein each detection unit further comprises a step-down circuit, when the touchscreen is working, the voltage of each sensor electrode are output to the second transistors via the step-down circuit, and voltage output by the step-down circuits are less than or about equal to the source-drain withstanding voltage of the second transistors.

20. The method of claim 19, wherein the touch panel further comprises a first substrate, a second substrate opposite to the first substrate, and a first conductive coating comprising a first transparent conductive layer, a second conductive coating comprising a second transparent conductive layer and a plurality of sensor electrodes disposed on the second transparent conductive layer along a first axis, the first and the second conductive coatings disposed on inner surfaces of the first and the second substrates respectively, wherein the second conductive coating is made from a carbon nanotube film comprising a plurality of carbon nanotubes arranged along the first axis, with extension of the axis of each carbon nanotube parallel with a second axis perpendicular to the first axis.