Patent ID: 6933922

Claim:
A data input device, comprising: a first proximity detector located at a first position on the device; a second proximity detector located at a second position on the device; and a processor in communication with the first and second proximity detectors, and configured to recognize an object-near condition only if both the first detector and the second detector detect an object in close proximity wherein the first proximity detector comprises a first electromagnetic energy source which can be selectively activated and deactivated and a first receptor which generates an output that varies over time in response to exposure to electromagnetic energy; the second proximity detector comprises a second electromagnetic energy source which can be selectively activated and deactivated and a second receptor which generates an output that varies over time in response to exposure to electromagnetic energy; and the processor is in communication with the first and second sources and with the first and second receptors, and configured to: activate and deactivate the first source and the second source, sample output of the first receptor and of the second receptor, store a first indicator for receptor output samples bearing a first relation to a threshold value of receptor output, store a second indicator for receptor output samples bearing a second relation to the threshold value, compare a first set of indicators stored during an interval when the first source is deactivated with a second set of indicators stored during an interval when the first source is activated, compare a third set of indicators stored during an interval when the second source is deactivated with a fourth set of indicators stored during an interval when the second source is activated, and recognize an object-near condition if the comparisons identify a triggering level of difference between the first and second sets and between the third and fourth sets.