Infrared sensor array sees a wider field of view, with low-noise imaging

September 11, 2014 // By Graham Prophet
Low cost infra-red (IR) arrays provide precise imaging data and detailed heat signatures for both static and dynamic objects can be derived, and find applications in security, automotive, building automation and consumer electronics.

With a 16 x 4 pixel configuration, the MLX90621 from Melexis can offer a field of view (FoV) of 100° x 25° - significantly greater than the company's previous generation of IR array products. It also has 4-times faster measurement speeds, equating to a dramatic reduction in the inherent noise levels present.

Factory calibrated to operate over a temperature range of -40°C to 85°C, this array can accurately measure object temperatures from -20°C to 300°C. Interface and control is managed via the device’s I2C digital interface. The speed is programmable, with a frame rate covering 0.5 Hz to 64 Hz supported. Noise vs. speed performance is characterised by 0.25K noise equivalent temperature difference (NETD) at a frequency of 16 Hz.

The improved FoV enables a single MLX90621, when applied inside a vehicle cabin, to simultaneously measure temperature profiles of both the passenger and driver, if suitably positioned on the centre-stack of the dashboard. This means that more effective automotive climate control can be achieved. For building air conditioning systems in most cases it was previously necessary to mount an IR sensor on a stepper-driven mechanical scanner to complete sweeps of the target cooling area. Thanks to the greater FoV exhibited by the MLX90621, the need for mechanical scanning is eliminated and a single fixed device is thus capable of imaging the whole area directly. The resulting reduction in cost, measurement time and system complexity afforded by this IR array opens up new opportunities and markets for cooling appliance designers.

The MLX90621 is available in a TO39 metal can package. The device is available in three FoV different options; 60° x 15°, 40° x 10° and 100° x 25°.