Reducing water influence on a touch-sensing device

• US 8,717,331 B2
• Filed: 12/21/2010
• Issued: 05/06/2014
• Est. Priority Date: 08/24/2010
• Status: Active Grant

• Current Assignee: Parade Technologies, Ltd.
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Hutnyk, Volodymyr, Kremin, Viktor, Kulyk, Taras, Karpin, Oleksandr
• Primary Examiner(s): Pappas, Claire X
• Assistant Examiner(s): STONE, ROBERT M
• Application Number:
  US12/974,991
• Publication Number:
  US 20120050214A1
• Time in Patent Office: 1,232 Days
• Field of Search: 345/174
• 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. A method comprising:

measuring a first capacitance on a selected one or more of a plurality of sensor elements of a touch-sensing device during a standard scan;

while measuring the first capacitance on the selected one or more of the plurality of sensor elements, coupling a reference voltage to non-selected ones of the plurality of sensor elements during the standard scan;

determining whether a touch is detected in view of the first capacitance measured during the standard scan;

in response to the touch not being detected in the standard scan, performing a subsequent standard scan; and

in response to the touch detected in the standard scan, performing a waterproof scan to test for a presence of water on the touch-sensing device, the waterproof scan comprising;

measuring a second capacitance on the selected one or more of the plurality of sensor elements during the waterproof scan;

while measuring the second capacitance on the selected one or more of the plurality of sensor elements, applying a shield signal to the non-selected ones of the plurality of sensor elements during the waterproof scan; and

outputting results of the standard scan when the touch is detected in view of the first capacitance measured during the standard scan and no water is detected in view of the second capacitance measured during the waterproof scan.

2. The method of claim 1, wherein said measuring the second capacitance comprises measuring the second capacitance using a first bus, and wherein said applying the shield signal comprises applying the shield signal to the non-selected ones of the plurality of sensor elements using a second bus.

3. The method of claim 2, 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.

4. The method of claim 1, wherein said measuring the second 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.

5. The method of claim 1, further comprising:

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

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

6. The method of claim 1, further comprising repeating said measuring while applying the shield signal for each of the plurality of sensor elements.