CAPACITIVE TOUCH SCREEN

• US 20120299874A1
• Filed: 08/08/2012
• Published: 11/29/2012
• 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 8,531,426 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. The conductive strip pattern allows that, when a touch range of each external conductive object on the mutual capacitive multi-touch screen is larger than a predetermined condition, capacitive coupling between each external conductive object and first conductive strip is greater than capacitive coupling between each external conductive object and second conductive strip, such that the proportion of a 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.

Claims

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

providing a capacitive touch sensitive display for operated by at least one external conductive object, including;

a plurality of exposed conductive strips, 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;

a display, wherein a rear shielding layer provided with a DC potential is not present between the display and the conductive strips;

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, and the difference suppresses noise coming from the display,

wherein the first conductive strips operatively provided with the driving signal is closer to the at least one external conductive object than the second conductive strips providing mutual capacitive coupling signals, and an insulating layer disposed between the first conductive strips and the second conductive strips.

2. The detection method according to claim 1, wherein capacitive coupling between each external conductive object and the first conductive strips is greater than capacitive coupling between each external conductive object and the second conductive strips.

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

wherein this conductive strip 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 first conductive strip is greater than capacitive coupling between each external conductive object and the second conductive strip, 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.

4. The detection method according to claim 1, wherein the exposed area of the first conductive strips is greater than the exposed area of the second conductive strips.

5. The detection method according to claim 1, wherein the conductive strips are arranged in a capacitive touch screen, and 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.

6. The detection method according to claim 1, wherein at least one zero-crossing point in the sensing information corresponds to the external conductive objects and each zero-crossing point is between a positive value and a negative value.

7. The detection method according to claim 1, wherein when a touch range of each external conductive object is larger than a predetermined condition, capacitive coupling between each external conductive object and the first conductive strip is greater than capacitive coupling between each external conductive object and the second conductive strip, and the exposed area of the first conductive strips covered by the touch range is greater than the exposed area of the second conductive strips covered by the touch range.

8. The detection method according to claim 1, wherein first conductive strips not provided with the driving signal are provided with the DC potential, and 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 potential via at least one second external conductive object in the external conductive objects increases as the number of second external conductive objects increases.

9. A capacitive touch screen, comprising:

a conductive pattern, including;

an upper conductive layer including a plurality of first conductive strips operatively provided a driving signal during mutual capacitive detection;

an lower conductive layer including a plurality of second conductive strips providing mutual capacitive coupling signals;

an insulating layer disposed between the first conductive strips and the second conductive strips; and

an insulating surface layer overlying on the upper conductive layer to receive approaching or touching of at least one external conductive object;

wherein the first conductive strips operatively provided with the driving signal is closer to the at least one external conductive object than the second conductive strips providing mutual capacitive coupling signals, and an insulating layer disposed between the first conductive strips and the second conductive strips.

10. The capacitive touch screen according to claim 9, wherein capacitive coupling between each external conductive object and the first conductive strips is greater than capacitive coupling between each external conductive object and the second conductive strips.

11. The capacitive touch screen according to claim 9, wherein the proportion of the driving signal flowing out of the first conductive strips via at least one first external conductive object in the external conductive objects and into the second conductive strips via at least one second external conductive object in the external conductive objects decreases as the number of second external conductive objects increases.

12. The capacitive touch screen according to claim 9, wherein the exposed area of the first conductive strips covered by the touch range is greater than the exposed area of the second conductive strips covered by the touch range, and the exposed area of the first conductive strips is greater than the exposed area of the second conductive strips.

13. The capacitive touch screen according to claim 9, 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 the display, and a rear shielding layer provided with a DC potential is not present between the display and the conductive strips, and the difference suppresses noise coming from the display.

14. The capacitive touch screen according to claim 13, 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.

15. The capacitive touch screen according to claim 9, wherein first conductive strips not provided with the driving signal are provided with a DC potential, and 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 potential via at least one second external conductive object in the external conductive objects increases as the number of second external conductive objects increases.

16. A capacitive touch screen, comprising a plurality of exposed conductive strips, 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, characterized by:

the conductive strip pattern allowing 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 first conductive strip is greater than capacitive coupling between each external conductive object and the second conductive strip, 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;

wherein the first conductive strips operatively provided with the driving signal is closer to the at least one external conductive object than the second conductive strips providing mutual capacitive coupling signals, and an insulating layer disposed between the first conductive strips and the second conductive strips.

17. The capacitive touch screen according to claim 16, wherein the exposed area of the first conductive strips covered by the touch range is greater than the exposed area of the second conductive strips covered by the touch range.

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

19. The capacitive touch screen according to claim 16, 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 the display, and a rear shielding layer provided with a DC potential is not present between the display and the conductive strips, and the difference suppresses noise coming from the display.

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

21. The capacitive touch screen according to claim 16, wherein first conductive strips not provided with the driving signal are provided with a DC potential, and 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 potential via at least one second external conductive object in the external conductive objects increases as the number of second external conductive objects increases.