Method and apparatus for determining when hands are under a faucet for lavatory applications

Abstract

A method of controlling a flow of liquid includes calibrating a PSD infrared sensor associated with the spout. The calibrating includes turning on the spout to thereby dispense a stream of liquid from the spout and into a stream space; emitting infrared energy from the PSD infrared sensor and toward the stream of liquid; sensing a first position of the infrared energy after the infrared energy has been reflected back to the sensor from the stream of liquid; storing first information based upon the first position of the reflected infrared energy; turning off the spout to thereby inhibit the liquid from being dispensed from the spout; sensing a second position of the infrared energy after the infrared energy has been reflected back to the sensor from an object that is fixed relative to the sensor; and storing second information based upon the second position of the reflected infrared energy. Infrared energy is emitted from the PSD infrared sensor and toward the stream space. A third position of the infrared energy after the infrared energy has been reflected back to the sensor is sensed. The spout is controlled dependent upon the first information, the second information and the third position.