Capacitive touch button with guard

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.

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.