Proximity sensor with adaptive threshold
First Claim
1. 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.
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Accused Products
Abstract
A proximity sensor measures receptor output with an energy source deactivated. The sensor then measures receptor output with the energy source activated. The measurements with the energy source activated are compared to the measurements with the energy source deactivated to compensate for the effect of ambient conditions. A near condition is recognized if the change between the two groups of measurements exceeds a designated value. To compensate for receptor output that may decrease after reaching a peak value during approach of an object, a near condition can be maintained until the change between the two groups of measurements no longer exceeds a different designated value. Multiple sensors can be used to avoid false near conditions caused by, e.g., placing a device equipped with the sensors next to a stationary object. In one embodiment, a sensor comprises an infrared light emitting diode and a phototransistor.
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Citations
15 Claims
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1. A data input device, comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification