Preventing unintentional activation of a touch-sensor button caused by a presence of conductive liquid on the touch-sensor button

• US 8,902,172 B2
• Filed: 12/07/2006
• Issued: 12/02/2014
• Est. Priority Date: 12/07/2006
• Status: Active Grant

• Current Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Peng, Tao, Li, Guanghai
• Primary Examiner(s): Boddie, William
• Assistant Examiner(s): SCHNIREL, ANDREW B
• Application Number:
  US11/636,060
• Publication Number:
  US 20080136792A1
• Time in Patent Office: 2,917 Days
• Field of Search: 345/173
• US Class Current: 345/173
• CPC Class Codes: G06F 3/04186 Touch location disambiguation
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: H03K 2217/960705 Safety of capacitive touch and proximity switches, e.g. increasing reliability, fail-safe
• CPC Class Codes: H03K 2217/960715 Rc-timing; e.g. measurement of variation of charge time or discharge time of the sensor
• CPC Class Codes: H03K 2217/960765 Details of shielding arrangements
• CPC Class Codes: H03K 2217/96077 comprising an electrode which is floating

Abstract

An apparatus and method for preventing unintentional activation of the one or more touch-sensor buttons caused by a presence of conductive liquid on the touch panel. The apparatus may include a processing device to prevent unintentional activations of one or more touch-sensor buttons caused by a presence of conductive liquid on the one or more touch-sensor buttons.

Claims

1. A method, comprising:

detecting a presence of conductive liquid on a touch panel that includes two or more touch-sensor buttons and an additional sensor element adjacent to the two or more touch-sensor buttons;

preventing unintentional activation, caused by the presence of the conductive liquid on the touch panel, of any of the two or more touch-sensor buttons, wherein preventing the unintentional activation comprises;

coupling each of the sensor elements of the two or more touch-sensor buttons to the additional sensor element;

measuring a collective capacitance on the sensor elements of the two or more touch-sensor buttons and the additional sensor element; and

determining whether the collective capacitance exceeds the rejection threshold;

activating any of the two or more touch-sensor buttons having a capacitance exceeding a presence threshold when the collective capacitance does not exceed a rejection threshold; and

deactivating any of the two or more touch-sensor buttons having a capacitance exceeding the presence threshold when the collective capacitance exceeds the rejection threshold.

2. The method of claim 1, wherein the presence of conductive liquid is present on an overlay of the touch panel, which is coupled to the two or more touch-sensor buttons.

3. The method of claim 1, wherein preventing the unintentional activation further comprises preventing the unintentional activation of the two or more touch-sensor buttons when a capacitance of the additional sensor element exceeds the rejection threshold.

4. The method of claim 1, wherein the two or more touch-sensor buttons each comprise a sensor element disposed in a first layer and a grounded conductor disposed in a second layer which is coupled to a system ground.

5. The method of claim 1, wherein the two or more touch-sensor buttons each comprise a sensor element disposed in first plane of a first layer and a grounded conductor disposed in a second plane of the first layer.

6. An apparatus, comprising:

a first sensor element;

two or more additional sensor elements, wherein the two or more additional sensor elements correspond to two or more touch-sensor buttons of a touch panel, and wherein the first sensor element is adjacent to the two or more touch-sensor buttons; and

a processing device, wherein the processing device is configured to;

prevent unintentional activations of the two or more touch-sensor buttons caused by a presence of conductive liquid on the touch panel using the first sensor element and the two or more additional sensor elements, wherein to prevent the unintentional activations the processing device is further configured to measure a collective capacitance on the two or more additional sensor elements and the first sensor element that is coupled thereto, and to determine whether the collective capacitance exceeds a rejection threshold;

activate the two or more touch-sensor buttons having a capacitance exceeding a presence threshold when the collective capacitance does not exceed the rejection threshold; and

deactivate the two or more touch-sensor buttons having a capacitance exceeding the presence threshold when the collective capacitance exceeds the rejection threshold.

7. The apparatus of claim 6, wherein the processing device is configured to detect the presence of conductive liquid on the touch panel.

8. The apparatus of claim 6, wherein at least a portion of the first sensor element is disposed between the two or more additional sensor elements.

9. The apparatus of claim 6, wherein the first sensor element is disposed to substantially surround the two or more additional sensor elements.

10. The apparatus of claim 6, wherein the touch panel is a control panel of a household appliance.

11. The apparatus of claim 10, wherein the household appliance is at least one of an oven, a stove, a microwave, a blender, a heater, a washer, a dryer, a toaster, or a dishwasher.

12. The apparatus of claim 6, wherein the two or more touch-sensor buttons are buttons of a mobile handset.

13. The apparatus of claim 7, wherein the processing device is configured to detect the presence of conductive liquid on the touch panel based on the measured capacitance of the first sensor element.