D6T MEMS Thermal Sensors User’s Manual (A284)
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The sensitive areas of elements are wider than the FOV-specification width. If the size of the
measured object is smaller than the sensitive area of an element, the background temperature of
objects other than the intended object will become a factor.
Our Thermal Sensors use a reference heat source (a blackbody furnace) to correct temperature
values. However, note that differences in emissivity due to composition of measured objects, surface
shape, and the occupancy ratio of objects within sensitive areas all affect temperature values.
Fig. 5. Distance as Factor of Fluctuations in Temperature Values
The measurable area (FOV) enlarges as the distance between the measured object increases.
The occupancy ratio of objects (people) in the FOV reduces as the distance increases. For this
reason, as the distance increases, the temperature values become more a representation (level of
influence) of the background temperature than the temperature of the intended object (people). In
other words, to correctly measure temperature of the intended objects, the measured object must
be sufficiently larger than the FOV area.
Using a MEMS Thermal Sensor as a human sensor is limited to close-distance applications for
simple determination of temperature value only. To increase the detection distance, determination
accuracy must be improved through software processing that factors temporal changes, position
of heat sources, human behavior information, and so on.
Distance: Close <<<<< Far
