Touch sensing circuit and method, touch screen and display device

• US 9,542,049 B2
• Filed: 06/30/2014
• Issued: 01/10/2017
• Est. Priority Date: 10/14/2013
• Status: Active Grant

• Current Assignee: BOE Technology Group Co., Ltd., Hefei BOE Optoelectronics Technology Company Limited (BOE Technology Group Co., Ltd.)
• Original Assignee: BOE Technology Group Co., Ltd., Hefei BOE Optoelectronics Technology Company Limited (BOE Technology Group Co., Ltd.)
• Inventors: Hu, Zuquan, Hu, Ming
• Primary Examiner(s): Patel, Sanjiv D
• Application Number:
  US14/415,696
• Publication Number:
  US 20160004364A1
• Time in Patent Office: 925 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G06F 3/047 using sets of wires, e.g. crossed wires
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers

Abstract

The invention provides a touch sensing circuit and method, a touch screen and a display device, the touch sensing circuit comprises: a touch sensing unit, an output control unit and a detection unit; the touch sensing unit is configured for providing a touch current, and transmitting the touch current to the output control unit; the output control unit is connected with a second control line, a read-out line, the touch sensing unit and the detection unit, for outputting the touch current to the detection unit; the detection unit is connected with a reference voltage terminal, an output terminal, the read-out line and the output control unit, for detecting significant change in the voltage output by the output control unit, thereby determining the location where the touch occurs. The detection accuracy of the detection sensing circuit in determining the occurrence of touch is improved.

Claims

1. A touch sensing circuit, comprising:

a touch sensing unit, an output control unit and a detection unit;

the touch sensing unit is connected with a first control line, a first power source, a second power source and the output control unit, for providing a touch current, and the touch current is transmitted to the output control unit;

the output control unit is connected with a second control line, a read-out line, the touch sensing unit and the detection unit, for outputting the touch current to the detection unit through the read-out line;

the detection unit is connected with a reference voltage terminal, an output terminal, the read-out line and the output control unit, for detecting significant change in a voltage output by the output control unit, thereby determining a location where a touch occurs, wherein

the touch sensing unit comprises;

a first transistor, a second transistor, a touch electrode, a first capacitor, and a second capacitor;

a second electrode of the first transistor is connected to a first terminal of the first capacitor;

a control electrode of the second transistor is connected to the touch electrode, a first electrode of the second transistor is connected to the first power source, and a second electrode of the second transistor is connected to the output control unit;

a second terminal of the first capacitor is connected to the touch electrode; and

a first terminal of the second capacitor is connected to the touch electrode, and a second terminal of the second capacitor is connected to the second power source.

2. The touch sensing circuit according to claim 1, wherein the touch sensing unit is also connected to a signal line, and

a control electrode of the first transistor is connected to the first control line, a first electrode of the first transistor is connected to the signal line, a second electrode of the first transistor is connected to a first terminal of the first capacitor.

3. The touch sensing circuit according to claim 1, wherein

a control electrode and a first electrode of the first transistor are both connected to the first control line, a second electrode of the first transistor is connected to a first terminal of the first capacitor.

4. The touch sensing circuit according to claim 2, wherein the second capacitor is a variable capacitor a capacitance of which is changed upon occurrence of touch, and the capacitance of the second capacitor is much larger than that of the first capacitor when a touch occurs.

5. The touch sensing circuit according to claim 3, wherein the second capacitor is a variable capacitor a capacitance of which is changed upon occurrence of touch, and the capacitance of the second capacitor is much larger than that of the first capacitor when a touch occurs.

6. The touch sensing circuit according to claim 2, wherein the output control unit comprises:

a third transistor;

a control electrode of the third transistor is connected to the second control line, a first electrode of the third transistor is connected to the second electrode of the second transistor, a second electrode of the third transistor is connected to the read-out line.

7. The touch sensing circuit according to claim 3 wherein the output control unit comprises:

a third transistor;

a control electrode of the third transistor is connected to the second control line, a first electrode of the third transistor is connected to the second electrode of the second transistor, a second electrode of the third transistor is connected to the read-out line.

8. The touch sensing circuit according to claim 6, wherein the detection unit comprises:

a third capacitor, a switch unit and an amplifier;

the third capacitor and the switch unit are parallel connected between an output terminal and a first terminal of the amplifier, a second terminal of the amplifier is connected to the reference voltage terminal.

9. The touch sensing circuit according to claim 7, wherein the detection unit comprises:

a third capacitor, a switch unit and an amplifier;

the third capacitor and the switch unit are parallel connected between an output terminal and a first terminal of the amplifier, a second terminal of the amplifier is connected to the reference voltage terminal.

10. The touch sensing circuit according to claim 8, wherein the first transistor, the second transistor and the third transistor are N-type thin film transistors.

11. The touch sensing circuit according to claim 9, wherein the first transistor, the second transistor and the third transistor are N-type thin film transistors.

12. A display device comprising a touch screen, wherein the touch screen comprising the touch sensing circuit according to claim 1.

13. A touch sensing method applied in a touch sensing circuit comprising:

a touch sensing unit, an output control unit and a detection unit;

the touch sensing unit is connected with a first control line, a first power source, a second power source and the output control unit, for providing a touch current, and the touch current is transmitted to the output control unit;

the output control unit is connected with a second control line, a read-out line, the touch sensing unit and the detection unit, for outputting the touch current to the detection unit through the read-out line;

the detection unit is connected with a reference voltage terminal, an output terminal, the read-out line and the output control unit, for detecting significant change in a voltage output by the output control unit, thereby determining a location where a touch occurs, wherein

the touch sensing unit comprises;

a first transistor, a second transistor, a touch electrode, a first capacitor, and a second capacitor;

a second electrode of the first transistor is connected to a first terminal of the first capacitor;

a control electrode of the second transistor is connected to the touch electrode, a first electrode of the second transistor is connected to the first power source, and a second electrode of the second transistor is connected to the output control unit;

a second terminal of the first capacitor is connected to the touch electrode; and

a first terminal of the second capacitor is connected to the touch electrode, and a second terminal of the second capacitor is connected to the second power source,

the touch sensing method comprising steps of;

providing touch current by the touch sensing unit under control of a first control line, a first power source and a second power source, and transmitting the touch current to the output control unit;

outputting the touch current to the detection unit through the read-out line, by the output control unit under control of a second control line;

under control of the reference voltage terminal, detecting significant change in the voltage output from the output control unit by the detection unit through the read-out line, thereby determining the location where the touch occurs.

14. The touch sensing method according to claim 13, wherein the step of providing touch current by the touch sensing unit under control of a first control line, a first power source and a second power source, and transmitting the touch current to the output control unit comprises:

the first transistor and the second transistor are turned on under control of the first control line, a voltage value of the touch electrode is changed when a touch occurs, so that a control electrode voltage of the second transistor is changed and touch current is generated.

15. The touch sensing method according to claim 14, wherein the step of outputting the touch current to the detection unit through the read-out line, by the output control unit under control of a second control line comprises:

the third transistor is turned on under control of the second control line, the touch current flowing through the second transistor is transmitted to the read-out line through the third transistor.

16. The touch sensing method according to claim 14, wherein the step of determining the location of touch by the detection unit through the read-out line under control of the reference voltage terminal comprises:

when the switch unit is turned on, the third capacitor is charged by the touch current output from the output control unit, a voltage across the third capacitor is changed and forms a voltage difference with the reference voltage terminal, the voltage difference is amplified by the amplifier, thereby outputting signal indicating the location of touch;

when the switch unit is turned off, the third capacitor is discharged and reset.