Image display systems

• US 20090231294A1
• Filed: 03/04/2009
• Published: 09/17/2009
• Est. Priority Date: 03/12/2008
• Status: Active Grant

• Current Assignee: InnoLux Corporation
• Original Assignee: TPO Displays Corporation (InnoLux Corporation)
• Inventors: Wu, Tse-Hung
• Granted Patent: US 8,294,678 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 3/03547 Touch pads, in which fingers can move on a surface
• CPC Class Codes: G06F 3/04182 Filtering of noise external to the device and not generated by digitiser components
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• CPC Class Codes: H03K 2217/960725 Charge-transfer

Abstract

Image display systems are provided, in which a touch sensing circuit includes at least one voltage storing unit to generate a corresponding voltage when a capacitance variation caused by a touch event occurs. The voltage storing unit includes a first capacitor having a first terminal coupled to an alternating current (AC) common voltage from a common electrode and a second terminal coupled to a first node, a first switching element having a first terminal coupled to the second terminal of the first capacitor and a second terminal coupled to the AC common voltage, and a second switching element having a first terminal coupled to the second terminal of the first capacitor.

Claims

1. An image display system, comprising:

a touch sensing circuit comprising at least one voltage storing unit to generate a corresponding voltage when a capacitance variation caused by a touch event occurs, wherein the voltage storing unit comprises;

a first capacitor having a first terminal coupled to an alternating current (AC) common voltage from a common electrode and a second terminal coupled to a first node;

a first switching element having a first terminal coupled to the second terminal of the first capacitor and a second terminal coupled to the AC common voltage; and

a second switching element having a first terminal coupled to the second terminal of the first capacitor.

2. The image display system as claimed in claim 1, wherein the voltage storing unit further comprises a second capacitor coupled between a ground terminal and the second terminal of the first capacitor.

3. The image display system as claimed in claim 1, wherein the first switching element is turned on and the AC common voltage is changed to a relatively high voltage level from a relatively low voltage level such that the first node is charged to the relatively high voltage level, during a first period.

4. The image display system as claimed in claim 3, wherein, during a second period, the first switching element is turned off and the AC common voltage is changed to the relatively low voltage level from the relatively high voltage level, such that the first node is pulled low to a first voltage level when the touch event does not occur, and the first node is pulled low to a second voltage level higher than the first voltage level when the touch event occurs.

5. The image display system as claimed in claim 1, wherein the touch sensing circuit further comprises an integration unit coupled to the second terminal of the second switching element to integrate the corresponding voltage thereby generating an output signal.

6. The image display system as claimed in claim 5, wherein the integration unit comprises:

a third switching element having a first terminal coupled to the second terminal of the second switching element, and a second terminal;

a second capacitor having a first terminal coupled to the second terminal of the third switching element, and a second terminal;

a fourth switching element having a first terminal coupled to the second terminal of the third switching element, and a second terminal coupled to a relatively low voltage level of the AC common voltage;

a fifth switching element having a first terminal coupled to the second terminal of the second capacitor, and a second terminal;

a sixth switching element having a first terminal coupled to the second terminal of the second capacitor, and a second terminal coupled to the relatively low voltage level;

an operational amplifier having an inversion input terminal coupled to the second terminal of the second capacitor, a non-inversion input terminal coupled to the relatively low voltage level, and an output terminal;

a third capacitor coupled between the inversion input terminal and the output terminal of the operational amplifier;

a seventh switching element coupled between the inversion input terminal and the output terminal of the operational amplifier; and

an eighth switching element coupled to the output terminal of the operational amplifier to output the output signal.

7. The image display system as claimed in claim 1, further comprising a touch panel, wherein the touch panel comprises the touch sensing circuit.

8. The image display system as claimed in claim 7, further comprising an electronic device, wherein the electronic device comprises a display panel displaying images and the touch panel interacting with users.

9. The image display system as claimed in claim 8, wherein the display panel is an organic light emitting display panel, a plasma display panel, a liquid crystal display or a TFT-driven display panel.

10. The image display system as claimed in claim 9, wherein the electronic device is a personal digital assistant, a display monitor, a notebook computer, a digital camera, a car display, a tablet PC or a mobile phone.

11. An image display system, comprising:

a touch sensing circuit comprising;

first and second voltage storing units each generating a corresponding voltage when a capacitance variation caused by a touch event occurs; and

an integration unit integrating the corresponding voltage generated by the first voltage storing unit to generate a first output signal during a first period, and integrating the corresponding voltage generated by the second voltage storing unit to generate a second output signal during a second period, wherein the first and second voltage storing units each comprises;

a first capacitor having a first terminal coupled to an alternating current (AC) common voltage from a common electrode, and a second terminal coupled to a first node;

a first switching element having a first terminal coupled to the second terminal of the first capacitor and a second terminal coupled to the AC common voltage; and

a second switching element having a first terminal coupled to the second terminal of the first capacitor.

12. The image display system as claimed in claim 11, wherein the first and second voltage storing units each further comprise a second capacitor coupled between a ground terminal and the second terminal of the first capacitor.

13. The image display system as claimed in claim 12, wherein the first switching element is turned on and the AC common voltage is changed to a relatively high voltage level from a relatively low voltage level such that the first node is charged to the relatively high voltage level, during a third period.

14. The image display system as claimed in claim 13, wherein, during a fourth period, the first switching element is turned off and the AC common voltage is changed to the relatively low voltage level from the relatively high voltage level, such that the first node is pulled low to a first voltage level when the touch event does not occur, and the first node is pulled low to a second voltage level higher than the first voltage level when the touch event occurs.

15. The image display system as claimed in claim 11, wherein the integration unit comprises:

a third switching element having a first terminal coupled to the second terminal of the second switching element, and a second terminal;

a second capacitor having a first terminal coupled to the second terminal of the third switching element, and a second terminal;

a fourth switching element having a first terminal coupled to the second terminal of the third switching element, and a second terminal coupled to a low voltage level;

a fifth switching element having a first terminal coupled to the second terminal of the second capacitor, and a second terminal;

a sixth switching element having a first terminal coupled to the second terminal of the second capacitor, and a second terminal coupled to the low voltage level;

an operational amplifier having an inversion input terminal coupled to the second terminal of the second capacitor, a non-inversion input terminal coupled to the low voltage level, and an output terminal;

a third capacitor coupled between the inversion input terminal and the output terminal of the operational amplifier;

a seventh switching element coupled between the inversion input terminal and the output terminal of the operational amplifier; and

an eighth switching element coupled to the output terminal of the operational amplifier to output the first and second output signals.