Proximity Sensor
Proximity sensors detect objects using a magnetic metal, non-magnetic metal (such as aluminum, copper ..) using inductive type sensors (Proximity Sensor Inductivity) and non-metallic object detection using sensor Proximity capacitive type (Capacitve Proximity Sensor). Model simultaneously available to meet most of the installation environment conditions: high temperature, low temperature, waterproof, anti-chemical ...
What is the proximity sensor?
Proximity sensors include all sensors detect objects without contact, such as switches based on the itinerary that the physical relationship between the sensor and to detect objects. Proximity sensors convert signals on the movement or appearance of the object into electrical signals. There are three detection systems to perform this conversion: the system using eddy currents are generated in the metal object by electromagnetic induction phenomenon, the system uses capacitance changes when approaching to detect objects, using the magnet system and the system switches from the community.
According to Japanese Industrial Standard (JIS) defines proximity sensor (JIS C 8201-5-2) in accordance with IEC 60947-5-2 is a switch to detect non-contact position.
Operating principle
Principle of operation of proximity sensors inductive type:
Proximity sensors detect the type inductive magnetic loss due to eddy currents generated on the surface of a conductor by an external magnetic field. Alternating electromagnetic field generated in the coil and impedance changes depending on the eddy currents on the surface of metal objects are detected.
Another method to detect small objects by detecting the phase of the frequency. All the sensors detect metal coils are used to detect the inductance changes. There is also a type of sensor impulse response, this type of emission under pulsed eddy current and detect the eddy current changes with the voltage generated in the coil.
Objects and sensors to detect when approaching each other, like the phenomenon of electromagnetic induction in a transformer.
The principle findings of the capacitance type sensor:
Proximity sensor detects the capacitance model changes the capacitance between sensor and object detection. Capacitance value depends on the size and distance of objects. A capacitive proximity sensor similar to the conventional capacitor with two electrodes of the parallel and the capacitance change between the second plate will be detected. A plate electrode was detected object and the other is a broken surface of the sensor. Objects can be detected depending on their dielectric value.
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