Capacitive touch button with guard
View Patent ↗An apparatus, such as a set-top box, includes at least one capacitive touch button with a guard feature that provides, among other things, the ability to detect and reject false touches. According to an exemplary embodiment, the apparatus includes a first conductive element that is capacitively isolated from ground, and a second conductive element that is capacitively isolated from ground and located adjacent to the first conductive element. A first sensor is coupled to the first conductive element and measures a change in capacitance between the first conductive element and ground due to a change in physical environment. A second sensor is coupled to the second conductive element and measures a change in capacitance between the second conductive element and ground due to the change in physical environment. A controller is coupled to the first sensor and the second sensor and determines a difference between the measured changes in capacitance of the first sensor and the second sensor.
1. An apparatus, comprising:
a first conductive element, the first conductive element capacitively isolated from ground;
a second conductive element, the second conductive element capacitively isolated from ground and located adjacent to edges of the first conductive element;
a first sensor coupled to the first conductive element, the first sensor measuring a change in capacitance between the first conductive element and ground due to a change in physical environment;
a second sensor coupled to the second conductive element, the second sensor measuring a change in capacitance between the second conductive element and ground due to the change in physical environment; and
a controller coupled to the first sensor and the second sensor, the controller determining a difference between the measured changes in capacitance of the first sensor and the second sensor,
wherein if the determined difference is equal to or exceeds a threshold, the controller determines that the change in physical environment represents a valid user input to the apparatus, and if the determined difference is less than the threshold, the controller determines that the change in physical environment does not represent a valid user input to the apparatus.
2. The apparatus of claim 1 , wherein:
the first conductive element represents a first portion of a capacitive touch button; and
the second conductive element represents a second portion of the capacitive touch button.
3. The apparatus of claim 2 , wherein the first portion of the capacitive touch button is a main portion of the capacitive touch button and the second portion of the capacitive touch button is a guard portion of the capacitive touch button.
4. The apparatus of claim 2 , wherein the capacitive touch button is a power button of the apparatus.
5. The apparatus of claim 1 , wherein:
the first conductive element is circular; and
the second conductive element is concentric with substantially all of the first conductive element.
6. The apparatus of claim 1 , wherein the threshold is a value that is twenty percent of the value of the change in capacitance between the second conductive element and ground.
7. The apparatus of claim 1 , wherein a gap between the first and second conductive elements is uniform along their respective surface edges.
8. The apparatus of claim 1 , wherein a gap between the first and second conductive elements is not uniform along their respective surface edges.
9. The apparatus of claim 1 , comprising a plurality of the first conductive elements, and wherein the second conductive element is configured as a unitary segment extending around the plurality of first conductive elements.
10. A method, comprising:
measuring a change in capacitance between a first conductive and ground due to a change in physical environment;
measuring a change in capacitance between a second conductive element and ground due to the change in physical environment, wherein the second conductive element is located adjacent to edges of the first conductive element;
determining a difference between the measured changes in capacitance;
determining that the change in physical environment represents a valid user input to an apparatus if the determined difference is equal to or exceeds a threshold; and
determining that the change in physical environment does not represent a valid user input to the apparatus if the determined difference is less than the threshold.
11. The method of claim 10 , wherein:
the first conductive element represents a first portion of a capacitive touch button of an apparatus; and
the second conductive element represents a second portion of the capacitive touch button.
12. The method of claim 11 , wherein the first portion of the capacitive touch button is a main portion of the capacitive touch button and the second portion of the capacitive touch button is a guard portion of the capacitive touch button.
13. The method of claim 11 , wherein the capacitive touch button is a power button of the apparatus.
14. The method of claim 10 , wherein:
the first conductive element is circular; and
the second conductive means is concentric with substantially all of the first conductive means.
15. The method of claim 10 , wherein:
the first conductive element comprises a plurality of conductive elements; and
the second conductive element is configured as a unitary segment extending around the plurality of conductive elements.
16. The method of claim 10 , wherein the threshold is a value that is twenty percent of the value of the change in capacitance between the second conductive element and ground.
17. The method of claim 10 , wherein a gap between the first and second conductive elements is uniform along their respective surface edges.
18. The method of claim 10 , wherein a gap between the first and second conductive elements is not uniform along their respective surface edges.
19. An apparatus, comprising:
first conductive means capacitively isolated from ground;
second conductive means capacitively isolated from ground and positioned adjacent to substantially all surface edges of the first conductive means;
means for measuring a change in capacitance between the first conductive means and ground due to a change in physical environment, and for measuring a change in capacitance between the second conductive means and ground due to the change in physical environment; and
means for determining a difference between the measured changes in capacitance,
wherein if the determined difference is equal to or exceeds a threshold, the determining means determines that the change in physical environment represents a valid user input to the apparatus, and
wherein if the determined difference is less than a threshold, the determining means determines that the change in physical environment does not represent a valid user input to the apparatus.
20. The apparatus of claim 19 , wherein:
the first conductive means represents a first portion of a capacitive touch button; and
the second conductive means represents a second portion of the capacitive touch button.
21. The apparatus of claim 20 , wherein the first portion of the capacitive touch button is a main portion of the capacitive touch button and the second portion of the capacitive touch button is a guard portion of the capacitive touch button.
22. The apparatus of claim 20 , wherein the capacitive touch button is a power button of the apparatus.
23. The apparatus of claim 19 , wherein:
the first conductive means is circular; and
the second conductive means is concentric with substantially all of the first conductive element.
24. The apparatus of claim 19 , wherein the threshold is a value that is twenty percent of the value of the change in capacitance between the second conductive element and ground.
25. The apparatus of claim 19 , wherein a gap between the first conductive means and second conductive means is uniform along their respective surface edges.
26. The apparatus of claim 19 , wherein a gap between the first conductive means and second conductive means is not uniform along their respective surface edges.
27. The apparatus of claim 19 , wherein the first conductive means comprises a plurality of the first conductive elements, and wherein the second conductive means is configured as a unitary segment extending around the plurality of first conductive elements.