REDUCING WATER INFLUENCE ON A TOUCH-SENSING DEVICE

• US 20120050214A1
• Filed: 12/21/2010
• Published: 03/01/2012
• Est. Priority Date: 08/24/2010
• Status: Active Grant

• Current Assignee: Parade Technologies, Ltd.
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Kremin, Viktor, Karpin, Oleksandr, Kulyk, Taras, Hutnyk, Volodymyr
• Granted Patent: US 8,717,331 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• 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 2203/04108 Touchless 2D- digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface without distance measurement in the Z direction
• CPC Class Codes: G06F 3/04186 Touch location disambiguation
• 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: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

A method and apparatus for reducing water influence on a touch-sensing device is described.

Claims

1. An apparatus, comprising:

a first bus configured to be coupled to a plurality of sensor elements of a touch-sensing device;

a second bus configured to be coupled to the plurality of sensor elements; and

capacitance-sensing circuitry coupled to the first and second buses, wherein the capacitance-sensing circuitry is configured to measure a capacitance on a selected one or more of the plurality of sensor elements using the first bus, while applying a shield signal to other non-selected ones of the plurality of sensor elements using the second bus.

2. The apparatus of claim 1, wherein the first bus is an analog bus and the second bus is a digital bus, and wherein the shield signal is a digital signal.

3. The apparatus of claim 1, wherein the shield signal has a substantially same amplitude as a signal used by the capacitance-sensing circuitry to measure the capacitance on one of the plurality of sensor elements.

4. The apparatus of claim 1, wherein the shield signal has a substantially same phase as a signal used by the capacitance-sensing circuitry to measure the capacitance on one of the plurality of sensor elements.

5. The apparatus of claim 1, wherein the capacitance-sensing circuitry is configured to apply the shield signal to the other non-selected ones of the plurality of sensor elements to form a substantially equipotential surface of the touch-sensing device for reducing water influence on the touch-sensing device.

6. The apparatus of claim 1, further comprising a processing device comprising the capacitance-sensing circuitry, wherein the processing device is configured to detect a presence of an object on the touch-sensing device.

7. The apparatus of claim 1, further comprising the touch-sensing device having the plurality of sensor elements.

8. The apparatus of claim 7, wherein the touch-sensing device is an Indium-tin-oxide (ITO) touch panel.

9. The apparatus of claim 7, wherein the touch-sensing device is a single-layer touch panel.

10. The apparatus of claim 7, wherein the touch-sensing device comprises a plurality of rows and a plurality of columns as the plurality of sensor elements, and wherein the capacitance-sensing circuitry is configured to scan each of the plurality of rows and each of the plurality of columns to detect a presence of an object on or in proximity to the touch-sensing device.

11. The apparatus of claim 10, wherein the capacitance-sensing circuitry is configured to scan a selected one or more of the plurality of rows and the plurality of columns while applying the shield signal to all other non-selected ones of the plurality of rows and plurality of columns.

12. The apparatus of claim 10, wherein the capacitance-sensing circuitry is configured to scan a selected one or more of the plurality of rows and the plurality of columns while applying the shield signal to less than all other non-selected ones of the plurality of rows and plurality of columns.

13. A method, comprising:

measuring a capacitance on a selected one or more of a plurality of sensor elements of a touch-sensing device; and

while measuring the capacitance on the selected one or more of the plurality of sensor elements, applying a shield signal to other non-selected ones of the plurality of sensor elements of the touch-sensing device.

14. The method of claim 13, wherein said measuring comprises measuring the capacitance using a first bus, and wherein said applying the shield signal comprises applying the shield signal to the other non-selected ones of the plurality of sensor elements using a second bus.

15. The method of claim 14, wherein the first bus is an analog bus and the second bus is a digital bus, and wherein the shield signal is a digital signal.

16. The method of claim 13, wherein said measuring the capacitance comprises supplying a first signal to the selected one or more of the plurality of sensor elements, and wherein the shield signal has a substantially same amplitude and phase as the first signal.

17. The method of claim 13, further comprising:

measuring a second capacitance on a second selected one or more of the plurality of sensor elements; and

while measuring the second capacitance on the second selected one or more of the plurality of sensor elements, applying the shield signal to other non-selected ones of the plurality of sensor elements.

18. The method of claim 13, further comprising repeating said measuring and said applying for each of the plurality of sensor elements.

19. An apparatus, comprising:

means for measuring a capacitance on a selected one or more of a plurality of sensor elements of a touch-sensing device; and

means for applying a shield signal to other non-selected ones of the plurality of sensor elements while measuring the capacitance on the selected one or more of the plurality of sensor elements.

20. The apparatus of claim 19, wherein the means for applying the shield signal forms an equipotential surface of the touch-sensing device to reduce water influence on the touch-sensing device.