CAPACITIVE TOUCH SCREEN

• US 20120169656A1
• Filed: 11/28/2011
• 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 8,614,688 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. The guarding pattern allows that, when a touch range of each external conductive object is larger than a predetermined condition, capacitive coupling between each external conductive object and the guarding pattern or capacitive coupling between each external conductive object and the first conductive strips and the guarding pattern is greater than capacitive coupling between each external conductive object and the second conductive strips.

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, wherein the conductive strips intersect with each other to form a grid with a plurality of exposing spaces;

a guarding pattern including a plurality of guarding conductive strips, each guarding conductive strip including a plurality of guarding connecting lines connecting a plurality of guarding conductive pads in series, wherein each space exposes at least one guarding conductive pad; and

simultaneously and continuously providing the driving signal to at least one first conductive strip, and providing a direct current (DC) signal to first conductive strips not driven by the driving signal and the guarding pattern; and

generating sensing information based on the mutual capacitive coupling signals provided by the second conductive strips each time the driving signal being provided.

2. The detection method according to claim 1, wherein the 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.

3. The detection method according to claim 1, wherein the guarding pattern includes a plurality of upper guarding conductive strips and a plurality of lower guarding conductive strips, and the first conductive strips and the upper guarding conductive strips are adjacent to each other on the same layer, while the second conductive strips and the lower guarding conductive strips are adjacent to each other on the same layer.

4. The detection method according to claim 1, wherein the guarding pattern includes a plurality of guarding conductive strips, and one of the first conductive strips or the second conductive strips are adjacent to the guarding conductive strips on the same layer, and the first conductive strips and the second conductive strips are disposed on different layers separated by an insulating intermediate layer.

5. The detection method according to claim 4, 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.

6. 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.

7. The detection method according to claim 2, 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.

8. The detection method according to claim 2, 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.

9. The detection method according to claim 2, 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.

10. The detection method according to claim 9, 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 three conductive strips.

11. 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; 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, wherein the conductive strips intersect with each other to form a grid with a plurality of exposing spaces;

a guarding pattern including a plurality of guarding conductive strips, each guarding conductive strip including a plurality of guarding connecting lines connecting a plurality of guarding conductive pads in series, wherein each space exposes at least one guarding conductive pad; and

wherein the DC signal is provided by a controller, the controller simultaneously and continuously provides the driving signal to at least one first conductive strip, and generates sensing information based on the mutual capacitive coupling signals provided by the second conductive strips each time the driving signal is provided.

12. The capacitive touch screen according to claim 11, wherein the 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.

13. The capacitive touch screen according to claim 11, wherein the guarding pattern includes a plurality of upper guarding conductive strips and a plurality of lower guarding conductive strips, and the first conductive strips and the upper guarding conductive strips are adjacent to each other on the same layer, while the second conductive strips and the lower guarding conductive strips are adjacent to each other on the same layer.

14. The capacitive touch screen according to claim 11, wherein the guarding pattern includes a plurality of guarding conductive strips, and one of the first conductive strips or the second conductive strips are adjacent to the guarding conductive strip on the same layer, and the first conductive strips and the second conductive strips are disposed on different layers separated by an insulating intermediate layer.

15. The capacitive touch screen according to claim 14, 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.

16. The capacitive touch screen according to claim 11, 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.

17. 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.

18. 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.

19. The capacitive touch screen according to claim 12, 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.

20. The capacitive touch screen according to claim 19, 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 three conductive strips.