Infra-red sensor array offers thermal imaging/detection

November 23, 2016 // By Graham Prophet
Melexis (Tessenderlo, Belgium) recently announced its MLX90640 infrared (IR) sensor array that offers a cost-effective alternative to more expensive high-end thermal cameras. It can provide advanced detection features where there is no requirement for detailed imaging.

The device is a thermopile-technology detector, but one in which Melexis has reduced the pixel size while retaining sensitivity; the company has applied internal signal processing to compensate for reduced signal/noise ratios. The sensor has 32 x 24 pixel-resolution, which Melexis says is suited to safety and convenience applications that include fire prevention systems, smart buildings, intelligent lighting, IP/surveillance cameras, HVAC equipment and vehicle seat occupancy detection. In the latter case, the sensor can provide information to control high-end vehicle comfort systems (HVAC).


The resolution is sufficient to detect, and thermally map, the presence of a person or persons in its field of view; but can be intentionally configured to be less than would be required to identify them. This can be an asset where there are issues of privacy. The sensor has a -40°C to 85°C operational temperature range and can measure object temperatures between -40°C and 300°C. Maintaining high levels of precision across its full measurement scale, this cost effective device delivers a typical target object temperature accuracy of ±1°C. It also exhibits superior noise performance, with a noise equivalent temperature difference (NETD) of 0.1K RMS at a 1Hz refresh rate. Unlike microbolometer alternatives, the sensor does not need frequent re-calibration, thus ensuring continuous monitoring and lowering system cost. Field-of-view (FoV) options comprise the standard 55° x 35° version and a 110° x 75° wide-angle version. The MLX90640 is supplied in a compact, 4-pin TO39 package incorporating the necessary optics. An I ²C-compatible digital interface simplifies integration.