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Detector Cuts Energy Consumption in HVAC Systems
Bridges gap between simple sensors and infrared cameras
Charles J. Murray, Senior Technical Editor -- Design News, October 13, 2009
A new sensor can tell the difference between humans and animals inside a room without the use of expensive infrared (IR) imaging cameras.
Known as the Cool Eye™ Thermopile Array, the device could serve as an energy conservation system, enabling a building's HVAC to autonomously switch off the heat when there's no one in a room, or turn up the air conditioning when a room is crowded. It could also inexpensively boost the intelligence of security systems, where its ability to distinguish between humans and animals would enable it to serve in an intruder alarm.
Engineers say the system's key advantage is its cost. At about $20, the device's price tag lies close to that of low-end sensors, but with performance reportedly similar to that of $2,000 infrared cameras.
"We're bridging the gap between dumb sensors and infrared cameras," says Wolfgang Schmidt, product leader for infrared sensing at PerkinElmer, maker of the Cool Eye. "This is not an IR camera, but its performance is a lot closer to the IR camera than to the simple sensor."
Cool Eye offers higher performance than the so-called "dumb" sensors because it employs a thermopile detector array containing 16 elements. The array includes lenses, and is available with an EEPROM and a microcontroller with an integrated 10-bit analog-to-digital converter. In contrast, typical IR sensors contain a couple of elements and don't incorporate focusing optics, Schmidt says.
Schmidt says the new 16-element detector can distinguish between humans and animals because it takes a picture that's divided into 16 parts, and then it uses the microcontroller to analyze all of the parts.
The device is already being used in an unspecified commercial air conditioning product and in other HVAC applications where it cuts energy consumption.
"This offers more than just an on-off response," Schmidt says. "It can look at the number of people in a room and help the HVAC system decide if it wants to go into a higher or lower operational mode."
PerkinElmer’s Cool Eye™ detector array is contained in a package about 9 mm in diameter, measuring about 7 mm high.
