CAPACITIVE TOUCH SCREEN

• US 20120169653A1
• Filed: 08/17/2011
• Published: 07/05/2012
• Est. Priority Date: 12/30/2010
• Status: Active Grant

• Current Assignee: eGalax_eMPIA Technology Inc.
• Original Assignee: eGalax_eMPIA Technology Inc.
• Inventors: CHANG, CHIN-FU
• Granted Patent: US 8,614,686 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 2203/04103 Manufacturing, i.e. details related to manufacturing processes specially suited for touch sensitive devices
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• CPC Class Codes: G06F 2203/04107 Shielding in digitiser, i.e. guard or shielding arrangements, mostly for capacitive touchscreens, e.g. driven shields, driven grounds
• CPC Class Codes: G06F 2203/04111 Cross over in capacitive digitiser, i.e. details of structures for connecting electrodes of the sensing pattern where the connections cross each other, e.g. bridge structures comprising an insulating layer, or vias through substrate
• 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 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• 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: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
• CPC Class Codes: G06F 3/0447 Position sensing using the local deformation of sensor cells

Abstract

The present invention provides a mutual capacitive multi-touch screen, which includes a guarding pattern and a conductive strip pattern exposed from each other. The conductive strip pattern includes a plurality of first conductive strips provided with a driving signal and a plurality of second conductive strips for providing mutual capacitive coupling signals, and the guarding pattern is provided with a DC signal.

Claims

1. A detection method for a capacitive touch screen, comprising:

providing a capacitive touch screen, including;

a conductive strip pattern having a plurality of conductive strips exposed from each other, the conductive strip pattern including;

a plurality of first conductive strips operatively provided with a driving signal during mutual capacitive detection; and

a plurality of second conductive strips providing mutual capacitive coupling signals, the first conductive strips and the second conductive strips being exposed and separated from each other; and

a guarding pattern provided with a direct current (DC) signal, and the guarding pattern and the conductive strip pattern being exposed and isolated from each other;

simultaneously and continuously providing the driving signal to at least one first conductive strip, and providing a DC signal to first conductive strips not driven by the driving signal; and

generating sensing information based on the mutual capacitive coupling signals provided by the second conductive strips each time the driving signal being provided, wherein each value of the sensing information is the difference between a pair of second conductive strips or the difference between signal differences of two pairs of conductive strips among three conductive strips, and the difference suppresses noise coming from a display,

wherein this conductive strip pattern allows that, when a touch range of each external conductive object on the capacitive touch screen is larger than a predetermined condition, the exposed area of the guarding pattern covered by each touch range is larger than the exposed area of the second conductive strips covered by the touch range or larger than the exposed area of the conductive strip pattern covered by the touch range, or the exposed areas of the guarding pattern and the first conductive strips covered by each touch range is larger than the exposed area of the second conductive strips covered by the touch range, such that the proportion of the driving signal flowing out of the first conductive strip via at least one first external conductive object in the external conductive objects and into the second conductive strip via at least one second external conductive object in the external conductive objects decreases as the number of second external conductive objects increases.

2. The detection method according to claim 1, wherein the second conductive strips have a plurality of openings, and the guarding pattern includes:

a plurality of guarding pads in the openings; and

a plurality of guarding connecting lines for providing the DC signal to the guarding pads in series and/or in parallel.

3. The detection method according to claim 1, wherein the first conductive strips and the second conductive strips have a plurality of openings, and the guarding pattern includes:

a plurality of guarding pads in the openings; and

a plurality of guarding connecting lines for providing the DC signal to the guarding pads in series and/or in parallel.

4. The detection method according to claim 1, wherein the guarding pattern includes a plurality of guarding conductive strips, and a guarding conductive strip is adjacent to each first conductive strip at either side thereof and each second conductive strip at either side thereof, the guarding conductive strips form the guarding pattern, wherein the outline of guarding conductive strips match the outlines of the adjacent first conductive strips or the second conductive strips.

5. The detection method according to claim 1, wherein the guarding pattern includes a plurality of guarding conductive strips, and a first conductive strip or a second conductive strip is adjacent to each guarding conductive strip at either side thereof, wherein the outlines of the first and second conductive strips match the outlines of the adjacent guarding conductive strips.

6. The detection method according to claim 1, wherein the guarding pattern includes a plurality of guarding conductive strips, the guarding conductive strips have a plurality of openings, wherein the intervals between the guarding conductive strips expose one of the first conductive strips and the second conductive strips, and the openings expose the other of the first conductive strips and the second conductive strips.

7. The detection method according to claim 1, wherein the guarding pattern and the first conductive strips are on the same layer, wherein the second conductive strips are on the same layer as the first conductive strips or on a layer further away from an insulating surface layer, wherein the external conductive objects approach or touch the insulating surface layer.

8. The detection method according to claim 1, wherein capacitive coupling between each external conductive object and the second conductive strips is smaller than capacitive coupling between the external conductive object and the guarding pattern or smaller than capacitive coupling between the external conductive object and the guarding pattern and the first conductive strips.

9. The detection method according to claim 1, wherein the predetermined condition is a width or an area, and the exposed area of the first conductive strips is greater than the exposed area of the second conductive strips.

10. The detection method according to claim 1, wherein the periphery of the capacitive touch screen is fixed to a display, and the portion of the capacitive touch screen not fixed to the display deforms under pressure, wherein each value of the sensing information is the difference between signal differences between the first two conductive strips and the latter two conductive strips among the three conductive strips.

11. The detection method according to claim 1, wherein the proportion of the driving signal flowing out of the first conductive strip via at least one first external conductive object in the external conductive objects and into the first conductive strip provided with the DC signal via at least one second external conductive object in the external conductive objects increases as the number of second external conductive objects increases.

12. A capacitive touch screen, comprising:

a conductive strip pattern having a plurality of conductive strips exposed from each other, the conductive strip pattern including;

a plurality of first conductive strips operatively provided with a driving signal during mutual capacitive detection, wherein first conductive strips not provided with the driving signal are provided with a direct current (DC) signal; and

a plurality of second conductive strips providing mutual capacitive coupling signals, the first conductive strips and the second conductive strips being exposed and separated from each other; and

a guarding pattern provided with the DC signal, and the guarding pattern and the conductive strip pattern being exposed and isolated from each other,

wherein the conductive strip pattern and the guarding pattern allow that, when a touch range of each external conductive object on the capacitive touch screen is larger than a predetermined condition, capacitive coupling between each external conductive object and the guarding pattern is larger than capacitive coupling between the external conductive object and the second conductive strips or larger than capacitive coupling between the external conductive object and the conductive strip pattern, or capacitive coupling between each external conductive object and the guarding pattern and the first conductive strips is larger than capacitive coupling between the external conductive object and the second conductive strips, such that the proportion of the driving signal flowing out of the first conductive strip via at least one first external conductive object in the external conductive objects and into the second conductive strip via at least one second external conductive object in the external conductive objects decreases as the number of second external conductive objects increases.

13. The capacitive touch screen according to claim 12, wherein the second conductive strips have a plurality of openings, and the guarding pattern includes:

a plurality of guarding pads in the openings; and

a plurality of guarding connecting lines for providing the DC signal to the guarding pads in series and/or in parallel.

14. The capacitive touch screen according to claim 12, wherein the first conductive strips and the second conductive strips have a plurality of openings, and the guarding pattern includes:

a plurality of guarding pads in the openings; and

a plurality of guarding connecting lines for providing the DC signal to the guarding pads in series and/or in parallel.

15. The capacitive touch screen according to claim 12, wherein the guarding pattern includes a plurality of guarding conductive strips, and a guarding conductive strip is adjacent to each first conductive strip at either side thereof and each second conductive strip at either side thereof, the guarding conductive strips form the guarding pattern, wherein the outline of guarding conductive strips match the outlines of the adjacent first conductive strips or the second conductive strips.

16. The capacitive touch screen according to claim 12, wherein the guarding pattern includes a plurality of guarding conductive strips, and a first conductive strip or a second conductive strip is adjacent to each guarding conductive strip at either side thereof, wherein the outlines of the first and second conductive strips match the outlines of the adjacent guarding conductive strips.

17. The capacitive touch screen according to claim 12, wherein the guarding pattern includes a plurality of guarding conductive strips, the guarding conductive strips have a plurality of openings, wherein the intervals between the guarding conductive strips expose one of the first conductive strips and the second conductive strips, and the openings expose the other of the first conductive strips and the second conductive strips.

18. The capacitive touch screen according to claim 12, wherein the guarding pattern and the first conductive strips are on the same layer, wherein the second conductive strips are on the same layer as the first conductive strips or on a layer further away from an insulating surface layer, wherein the external conductive objects approach or touch the insulating surface layer.

19. The capacitive touch screen according to claim 12, wherein the exposed area of the guarding pattern covered by the touch range is larger than the exposed area of the second conductive strips covered by the touch range, or and the exposed areas of the first conductive strips provided with the DC signal and the guarding pattern covered by the touch range is larger than the exposed area of the second conductive strips covered by the touch range.

20. The capacitive touch screen according to claim 12, wherein the predetermined condition is a width or an area, and the exposed area of the first conductive strips is greater than the exposed area of the second conductive strips.

21. The capacitive touch screen according to claim 12, further comprising a control circuit for performing the following operations:

simultaneously and continuously providing the driving signal to at least one first conductive strip; and

generating sensing information based on the mutual capacitive coupling signals provided by the second conductive strips each time the driving signal being provided, wherein each value of the sensing information is the difference between a pair of second conductive strips or the difference between signal differences of two pairs of conductive strips among three conductive strips,

wherein the capacitive touch screen is fixed to a display, and a rear shielding layer coupled to the DC potential is not present between the display and the conductive strips, and the difference suppresses noise coming from the display.

22. The capacitive touch screen according to claim 21, wherein the periphery of the capacitive touch screen is fixed to the display, and the portion of the capacitive touch screen not fixed to the display deforms under pressure, wherein each value of the sensing information is the difference between signal differences between the first two conductive strips and the latter two conductive strips among the three conductive strips.

23. The capacitive touch screen according to claim 12, wherein the proportion of the driving signal flowing out of the first conductive strip via at least one first external conductive object in the external conductive objects and into the first conductive strip provided with the DC signal via at least one second external conductive object in the external conductive objects increases as the number of second external conductive objects increases.