Diffuse background suppression (BGS) photoelectric sensors are used in applications where accurate differentiation between the target and potentially interfering backgrounds is essential. As with all such set-ups, when using this technique it is vital that only the target is sensed, regardless of the colour, surface and shape of the background and target.
Contrinex claims that its series 3131 range sets new standards in this field. Tough and compact, these sensors are built in a package measuring only 30 x 30 x 15mm and have a long sensing distance of 200mm. The precision background suppression can be adjusted in small increments down to 15mm and, because the sensors have a tiny blind zone, targets can be sensed down to 1mm from the lens. Most importantly, the sensors are immune to the colour, shape and surface texture of the background beyond the set target detection point, thereby ensuring stable, long-term reliability.
The 3131 series sensors have a red spot light that helps alignment with the target, an amber LED that indicates detection, and a green LED that confirms the optimum set-up. A 12-turn potentiometer adjustment is claimed to provide an extremely accurate setting of the background cut-off position and a narrow, focused beam prevents the detection of any adjacent objects or unwanted features that are close to the target.
These new Contrinex sensors have a high immunity to stray light sources and voltage overload, as well as protection against short circuits and induction spikes. The operating frequency is 500Hz and the switched current rating is 200mA. They also have a wide operating supply voltage from 10-36V DC, a stable sensing range from 25degC to 55degC and they are sealed to IP67.