Capacitive sensors detect virtually any material (paper, cardboard, plastic, etc.) at any operating distance up to 10mm. They are also suitable for detection of metallic or fluid objects.
sensing with an extremely long life.
Basic Mode of Operation:
The heart of the capacitive sensor is an oscillator with open capacitor which generates an electrostatic field. The oscillator does not oscillate if there is no object in the vicinity. If the metallic or non-metallic object to be detected approaches, the capacitance increase and oscillation starts. A trigger circuit detects this change and trips the output signal.
Since different materials influence the electrostatic field differently, the capacitive sensors should be adjusted accordingly during installation in order to achieve optimum operability. One typical application of capacitive sensors is the detection of fluids in non-metallic containers, e.g. in plastic tanks. Sensors adjustment suppresses any influences resulting from the tank wall.