Non-contact IR sensors detect occupancy without movement
19 September 2012
Omron Electronic Components has introduced a non-contact MEMS thermal sensor that can reliably detect the presence of humans in an area without the need for movement. The ultra-sensitive sensor offers an alternative to pyroelectric sensors or PIR detectors in home automation, building automation, healthcare, security and industrial applications.
The new Omron D6T is a super-sensitive infrared temperature sensor that makes full use of proprietary Omron MEMS sensing technology. Most human presence sensors rely on movement, but the D6T is able to detect occupation by sensing body heat and provides a more reliable basis for switching off lighting, air conditioning and other services when the space is empty. Conventional sensors often fail to distinguish between an unoccupied space and a stationary person. This feature is a particular issue in healthcare system design, when detecting the presence of bed-bound patients in a room.
As D6T sensors are able to monitor the temperature of a room, they can also be used to control the level of heating and air conditioning systems and maintain optimal room temperature levels without wasting energy. Unusual changes in temperature can also be used in other ways, for example to detect line stoppages, identify hot spots before a fire breaks out or in clinical applications to check whether a patient has left the bed.
While standard thermal sensors are only able to measure temperature at one contact point, the D6T can measure the temperature of an entire area contactlessly. Signals generated by infrared rays are extremely weak. To achieve reliable detection, Omron has developed and manufactured every part of the new high sensitivity thermal sensor in-house, from the MEMS sensors to application-specific integrated circuits and other application-specific parts.
The technology behind Omron’s D6T thermal sensors combines a MEMS micro-mirror structure for efficient IR radiation detection with a high-performance silicon lens to focus the infrared rays onto its thermopiles. Proprietary application-specific integrated circuits then make the necessary computations and convert sensor signals into digital outputs. All components were developed in-house and are fabricated in Omron’s own MEMS facilities. The result is high ±1.5degC accuracy with excellent noise immunity (measured as noise equivalent temperature difference) of 140mK.
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