Importance

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Abstract

An electronically controlled automatic faucet has a pulsed infrared beam intersecting the water stream discharged by the faucet. Infrared signals reflected from the water stream are thus detected in addition to any signals reflected from a user's hand(s). A reasonable approximation of the signal received from the water stream alone is subtracted from the sum of all detected signals whenever water is flowing in order to provide a compensated proximity signal. This compensation method, which may be implemented in hardware or software, prevents a shift in the sensor's sensitivity during periods when water is flowing, and eliminates the possibility that water flow might 'lock-on' once initiated. Compensating for water flow improves sensor performance by allowing the infrared detection field to encompass a larger volume of space where a user's hands might be found. In addition, the same, or similar, hardware can be used to detect a user's hand motion. The disclosed motion detection method can be used alone, or it can be used as an adjunct to the water stream compensation method, in which case it prevents extended intervals of water flow that could otherwise occur when foreign objects are left in view of the sensor.

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First Claim