SENSING CIRCUIT FOR TOUCH PANEL

• US 20100053106A1
• Filed: 08/27/2009
• Published: 03/04/2010
• Est. Priority Date: 08/28/2008
• Status: Abandoned Application

• Current Assignee: Wintek Corporation
• Original Assignee: Wintek Corporation
• Inventors: Liao, Wen-Tui, Wang, Wen-Chun, Chan, Chien-Ting
• Application Number:
  US12/548,890
• Publication Number:
  US 20100053106A1
• Time in Patent Office: Days
• US Class Current: 345/173
• 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 3/044 by capacitive means
• CPC Class Codes: G06F 3/0447 Position sensing using the local deformation of sensor cells

Abstract

A sensing circuit for a touch panel is disclosed. The sensing circuit includes a switching device, a passive device and a sensing device. The switching device receives an input signal and outputs the input signal according to a control signal. The passive device couples to the switching device. The sensing device couples to the switching device to form a node, receives the input signal to generate a reference voltage on the node, and changes the value of the reference voltage to generate a target voltage according to a touching pressure on a preset position on the touch panel from a user.

Claims

1. A sensing circuit for a touch panel, comprising:

a switching device for receiving an input signal and outputting the input signal according to a control signal;

a passive device coupling to the switching device; and

a sensing device coupling to the switching device to form a node for receiving the input signal to generate a reference voltage on the node and to change the value of the reference voltage to generate a target voltage according to a touching pressure on at least a preset position on the touch panel from at least a user.

2. The circuit according to claim 1, further comprising:

a calculator for receiving and converting the target voltage to generate an output voltage.

3. The circuit according to claim 1, wherein the switching device comprises at least one control terminal, at least one input terminal, and at least one output terminal and the passive device has one terminal coupling to the output terminal of the switching device and the other terminal coupling to the input or control terminal of the switching device.

4. The circuit according to claim 1, wherein the voltage level of the input signal and the voltage level of the control signal have a preset relation.

5. The circuit according to claim 1, wherein one or both of the input signal and the control signal are scan line signals.

6. The circuit according to claim 1, wherein one or both of the input signal and the control signal are generated by an external device.

7. The circuit according to claim 1, wherein the switching device is a semiconductor device or thin film transistor

8. The circuit according to claim 1, wherein the passive device is a capacitor or a capacitor formed by feed-through effect.

9. A sensing circuit for a touch panel, comprising:

a switching device comprising at least one control terminal, at least one input terminal, and at least one output terminal wherein the input terminal receives an input signal, the control terminal receives a control signal, and the status of the switching device is determined by the control signal;

a first capacitor having one terminal coupling to the output terminal of the switching device and the other terminal coupling to the input terminal of the switching device; and

a second capacitor having one terminal coupling to the output terminal of the switching device to form a node and the other terminal coupling to a common point (VCOM);

wherein a reference voltage is generated on the node when the switching device is turned on and the second capacitor changes the reference voltage to generate a target voltage according to whether at least a preset position on the touch panel is touched or not, or the extent of touching the preset position.

10. The circuit according to claim 9, wherein a preset voltage is generated on the node when the switching device is turned off, in order to achieve a reset function.

11. The circuit according to claim 9, further comprising:

a calculator for processing and converting the target voltage to generate an output voltage.

12. The circuit according to claim 9, wherein the voltage level of the input signal and the voltage level of the control signal have a preset relation.

13. The circuit according to claim 9, wherein the input signal and the control signal are synchronized scan line signals or successive scan line signals.

14. The circuit according to claim 9, wherein one or both of the input signal and the control signal are scan line signals.

15. The circuit according to claim 9, wherein one or both of the input signal and the control signal are generated by an external device.

16. The circuit according to claim 9, wherein the switching device is a semiconductor device or thin film transistor and the second capacitor is a variable capacitor.

17. A touch panel, comprising:

a plurality of pixels wherein each and every pixel corresponds to a preset position of the surface of the panel, one or a plurality of the pixels correspond to a sensing circuit, and the sensing circuit comprises;

a switching device, the on or off state of which is controlled by at least a signal;

a first capacitor coupling to two terminals of the switching device; and

a sensing device coupling to one terminal of the switching device to form a node wherein a reference voltage is generated one the node when the switching device is on and the sensing device changes the reference voltage to generate a target voltage according to whether the preset position is touched or not, or the extent of touching the preset position.

18. The touch panel according to claim 17, further comprising:

a plurality of circuit blocks to cooperate with the operation of the pixels.

19. The touch panel according to claim 17, wherein the sensing circuit further comprises a calculator for processing and converting the target voltage to generate an output voltage.

20. The touch panel according to claim 17, wherein the switching device is a semiconductor device or thin film transistor, and the sensing device is a variable capacitor, and the first capacitor is formed by feed-through effect.