Transcription of Capacitive Proximity Sensors Theory of Operation
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Capacitive Proximity Sensors Theory of Operation
54 Capacitive Proximity SensorsTheory of OperationCapacitive Proximity Sensors are similar to inductive proximitysensors. The main difference between the two types is thatcapacitive Proximity Sensors produce an electrostatic fieldinstead of an electromagnetic field. Capacitive proximityswitches will sense metal as well as nonmetallic materials suchas paper, glass, liquids, and sensing surface of a Capacitive sensor is formed by twoconcentrically shaped metal electrodes of an unwoundcapacitor. When an object nears the sensing surface it entersthe electrostatic field of the electrodes and changes thecapacitance in an oscillator circuit. As a result, the oscillatorbegins oscillating. The trigger circuit reads the oscillator samplitude and when it reaches a specific level the output stateof the sensor changes. As the target moves away from thesensor the oscillator s amplitude decreases, switching thesensor output back to its original Target andStandard targets are specified for each Capacitive sensor.
54 Capacitive Proximity Sensors Theory of Operation Capacitive proximity sensors are similar to inductive proximity sensors. The main difference between the two types is that
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