Capacitive Sensing Apparatus and Method Applied to Touch Screen Using the Capacitive Sensing Apparatus

• US 20110074728A1
• Filed: 09/02/2010
• Published: 03/31/2011
• Est. Priority Date: 09/29/2009
• Status: Active Grant

• Current Assignee: Ili Technology Corp. (MediaTek, Inc.)
• Original Assignee: MStar Semiconductor Incorporated (MediaTek, Inc.)
• Inventors: LIU, Chi Kang
• Granted Patent: US 9,235,297 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: G09G 3/3655 Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors

Abstract

A capacitive touch screen sensing apparatus is provided. The apparatus includes a protecting layer; a sensing layer under the protecting layer for sensing a touch to generate a position signal; and a DC common voltage signal layer electrically connected with a DC voltage for shielding against signal interferences.

Claims

1. A capacitive touch sensing apparatus, comprising:

a protecting layer;

a first sensing layer, disposed under the protecting layer, for sensing a touch to generate a position signal; and

a direct-current (DC) common voltage signal layer electrically connected with a DC voltage for shielding against signal interference.

2. The apparatus according to claim 1, wherein the first sensing layer comprises a plurality of capacitors, disposed under the protecting layer, for sensing the touch to generate the position signal.

3. The apparatus according to claim 1, wherein the first sensing layer comprises an indium-tin oxide (ITO) shielding layer disposed under the protecting layer for sensing the touch to generate the position signal.

4. The apparatus according to claim 1, further comprising an LCD panel, disposed above the DC common voltage signal layer, for displaying image data by dot inversion.

5. The apparatus according to claim 1, wherein the protecting layer is made of glass.

6. The apparatus according to claim 1, further comprising a display controller coupled to the DC common voltage signal layer for generating a source driving signal, wherein a source displacement of the source driving signal is symmetrical to the DC voltage.

7. The apparatus according to claim 1, further comprising a second sensing layer, deployed under the sensing layer, the second sensing layer being used for sensing cooperatively with the sensing layer the touch to generate the position signal.

8. The apparatus according to claim 1, further comprising a sensing protection layer, disposed above the DC common voltage signal layer, for protecting the sensing layers.

9. The apparatus according to claim 8, wherein the sensing protection layer is made of glass.

10. A capacitive touch sensing method, comprising:

applying a DC common voltage signal to a DC common voltage signal layer on a small-sized panel of a portable device;

generating a driving signal symmetric to the DC common voltage signal to drive a driver; and

sensing a touch to output a position signal.

11. The method according to claim 10, wherein the DC common voltage signal is a DC signal.

12. The method according to claim 10, further comprising providing two sensing layers for cooperatively sensing the touch.

13. The method according to claim 10, further comprising providing a protecting layer for protecting the small-sized panel.

14. The method according to claim 10, wherein the small-sized panel displays by dot inversion.

15. The method according to claim 10, further comprising generating the driving signal by a plurality of deep N-wells.

16. A touch screen, comprising:

an LCD panel;

a touch panel, for generating a sensing signal in response to a touch;

a display controller, for processing an image signal to generate a panel control signal, the panel control signal comprising a constant common voltage; and

a sensing circuit, coupled to the touch panel, for receiving the sensing signal to generate a position signal.

17. The touch screen according to claim 16, wherein the touch panel comprises a first sensing layer.

18. The touch screen according to claim 16, wherein the touch panel further comprises a second sensing layer.

19. The touch screen according to claim 18, wherein the touch panel further comprises a sensing protection layer.

20. The touch screen according to claim 16, wherein the constant common voltage is a DC voltage.