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

• US 20080136792A1
• Filed: 12/07/2006
• Published: 06/12/2008
• 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: Li, Guanghai, Peng, Tao
• Granted Patent: US 8,902,172 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• 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 one or more touch-sensor buttons; and

preventing unintentional activation of the one or more touch-sensor buttons when the presence of conductive liquid is detected on the touch panel.

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 one or more touch-sensor buttons.

3. The method of claim 1, wherein the one or more touch-sensor buttons each comprise a sensor element, and wherein preventing unintentional activation comprises preventing unintentional activation of the one or more touch-sensor buttons using an additional sensor element.

4. The method of claim 3, wherein preventing the unintentional activation comprises:

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

measuring a capacitance on the one or more touch-sensor buttons and the additional sensor element; and

determining whether the capacitance is greater than a rejection threshold.

5. The method of claim 4, wherein preventing the unintentional activation further comprises preventing the unintentional activation of the one or more touch-sensor buttons when the capacitance is greater than the rejection threshold.

6. The method of claim 3, wherein preventing the unintentional activation comprises:

measuring a capacitance on the additional sensor element; and

determining whether the capacitance is greater than a rejection threshold.

7. The method of claim 6, wherein preventing the unintentional activation further comprises preventing the unintentional activation of the one or more touch-sensor buttons when the capacitance is greater than the rejection threshold.

8. The method of claim 3, wherein preventing the unintentional activation comprises:

determining whether a first sensor element of a first touch-sensor button of the one or more touch-sensor buttons is activated;

determining whether a second sensor element of the second touch-sensor button of the one or more touch-sensor buttons is activated; and

determining whether the additional sensor element is activated.

9. The method of claim 8, wherein preventing the unintentional activation comprises:

determining that neither the first or second touch-sensor buttons has been activated when the first and second sensor elements are not activated, regardless of whether the additional sensor element is activated;

determining that the first touch-sensor button has been activated when the first sensor element is activated and the additional sensor element is not activated;

determining that the second touch-sensor button has been activated when the second sensor element is activated and the additional sensor element is not activated;

determining that the first touch-sensor button and the second touch-sensor button have been activated when the first and second sensor elements are activated and the additional sensor element is not activated; and

determining that neither the first or second touch-sensor buttons have been activated when the additional sensor element is activated, regardless of whether the first sensor element has been activated, and regardless of whether the second sensor element has been activated.

10. The method of claim 1, wherein the one 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.

11. The method of claim 1, wherein the one 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, and wherein preventing unintentional activation comprises preventing unintentional activation of the one or more touch-sensor buttons using an additional sensor element.

12. The method of claim 11, wherein preventing unintentional activation further comprises:

measuring a capacitance on the additional sensor element; and

determining whether the capacitance is greater than a rejection threshold.

13. The method of claim 12, wherein preventing the unintentional activation further comprises preventing the unintentional activation of the one or more touch-sensor buttons when the capacitance is greater than the rejection threshold.

14. An apparatus, comprising:

a first sensor element;

one or more additional sensor elements, wherein the one or more additional sensor elements correspond to one or more touch-sensor button of a touch panel; and

a processing device, wherein the processing device is configured to prevent unintentional activations of the one or more touch-sensor buttons caused by a presence of conductive liquid on the touch panel using the first sensor element.

15. The apparatus of claim 14, wherein the processing device is configured to detect the presence of conductive liquid on the touch panel.

16. The apparatus of claim 14, wherein the first sensor element is disposed between the one or more additional sensor elements.

17. The apparatus of claim 14, wherein the first sensor element is disposed to substantially surround the one or more additional sensor elements.

18. The apparatus of claim 14, wherein the touch panel is a control panel of a household appliance.

19. The apparatus of claim 18, 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.

20. The apparatus of claim 14, wherein the one or more touch-sensor buttons are buttons of a mobile handset.

21. The apparatus of claim 15, wherein the processing device is configured to measure the capacitance on the first sensor element to detect the presence of conductive liquid on the touch panel, and to determine whether the capacitance is greater than a rejection threshold.

22. An apparatus, comprising:

means for detecting a presence of conductive liquid on a touch panel that includes one or more touch-sensor buttons; and

means for preventing unintentional activation of the one or more touch-sensor buttons when the presence of conductive liquid is detected on the touch panel.

23. The apparatus of claim 22, further comprising means for increasing safety of a household appliance that includes the means for detecting the presence of conductive liquid on the touch panel and the means for preventing unintentional activation.

24. An apparatus, comprising:

a first sensor element disposed in a first layer;

a first surface of an overlay disposed on the first layer; and

a ground disposed in a second layer, wherein a distance between a second surface of the overlay and ground is configured to prevent unintentional activation of the first sensor element caused by a presence of the conductive liquid on a second surface of the overlay.

25. The apparatus of claim 24, further comprising an insulating layer between the first layer and the second layer.

26. A method, comprising:

disposing a first sensor element of conductive material in a first layer;

disposing an overlay on the first sensor element; and

disposing a ground conductor on a second layer, wherein a distance between a second surface of the overlay and ground conductor is configured to prevent unintentional activation of the first sensor element caused by a presence of the conductive liquid on a second surface of the overlay.

27. The method of claim 26, further comprising disposing a substrate, wherein the disposing the first layer comprises disposing the first layer to one side of the substrate, and wherein disposing the ground conductor comprises disposing the ground conductor to the opposite side of the substrate.

28. The method of claim 26, further comprising disposing an additional capacitor sensor element of conductive material in the first layer.