Hands Free Faucets-The Sensors and Electronic Controls
If the diaphragm is misunderstood and maligned, the electronic sensor component of automatic faucets by comparison is mired by hate and loathing of many in the plumbing industry. There seems to be an aura of mystery surrounding these sensors somewhat reminiscent of that exhibited towards personal computers and cellular phones when they first came into use. Well I'd like to do my part in dispelling this mystery first by taking it away on a long, hopefully entertaining, explanation, and then by bringing it all home to you. Feel free to email me and let me know if I did a good job, no hate letters please.
Automatic faucets are presence sensors and not motion sensors. They employ Active Infrared technology which senses "presence" and not "movement" of objects. Active infrared technology, like the name implies is actively emitting infrared light and actively waiting for this light to come back to it. On the frequency spectrum, infrared light lies between radio waves and light waves that are visible to the human eye. To achieve the task of emitting and receiving, faucet sensors employ 2 key components: an emitter/transmitter and a collector/receiver each about ¼" in diameter and 5/16"long or smaller. These components are housed within the sensor capsule that is located either at the neck of the faucet spout, in a separate sink hole to the side of the faucet spout, or in a special compartment up next to the aerator. The emitter is constantly emitting infrared light in a blinking method, that is, the emitter is constantly blinking in the same way that turn signals on automobiles blink when the turn signal lever is engaged. The collector on the other hand, is always ready to receive (collect) this blinking light, and when it does, the control electronics take a factory preset action, in the case of battery powered faucets, the control electronics send an electrical pulse to the solenoid valve asking it to open. When the collector no longer receive the blinking light, the control electronics will then send yet another electrical pulse to the solenoid, this time, asking the solenoid to close. Since the emitter emits infrared light in a narrow and focused beam (imagine the focusing apparatus on a common household flash light), and since the collector also receives infrared light in a straight and narrow beam, and since both emitter and collector point in the same direction never in plane view of one another, the only way that the collector can receive the blinking light that is emitted by the emitter is to place a reflective object in the path of the beam, in most cases human hands.
Some may read the earlier paragraph and immediately conclude that this automatic faucet "thing" is advanced technology, too complicated for plumbing purposes, maybe even extreme, and should never be used in any consumer level products. This assessment by some is not fair and, more notably, far from the truth. In fact this technology has been around for quite some time. Your TV remote control employs the same active infrared technology that your automatic faucet does, sometimes the same exact emitter and collector component. In the case of a remote control the emitter is located inside the remote control itself and at the end that points at the TV, whereas the collector is located inside the TV generally hidden behind an amber color transparent plastic guard.