Proximity switch working principle

Proximity switch working principle

Proximity switches are also called proximity sensors . Sensor can devided into inductive、 capacitive、simulative 、hall and magentic type . Sensor can be used together with PLC 、SCM、Electronic counters、SSR relays and other products.

The inductive proximity sensor is composed of high-frequency oscillation, detection, amplification, triggering and output circuits. The oscillator generates an alternating electromagnetic field on the detection surface of the sensor. When a metal object approaches its detection surface, the eddy current generated in the metal absorbs the energy of the oscillator, which weakens the vibration and even stops it. The two states of oscillation and vibration stop of the oscillator are converted into electrical signals and converted into binary switching signals by the shaping amplifier, and then output after power amplification.

The capacitive proximity sensor is composed of a high-frequency oscillator and an amplifier. A capacitor is formed between the detection surface of the sensor and the ground, which participates in the work of the oscillation circuit, and is initially in a vibration-stop state. When the object approaches its detection surface, the capacitance of the loop changes, and the high-frequency oscillator oscillates, and the two states of oscillation and vibration stop are converted into electrical signals and converted into binary switching signals by the amplifier. Analog sensor (also known as linear displacement sensor), when the metal object approaches its detection surface, as the distance changes, it outputs an electrical signal that changes linearly with the distance, so as to achieve the purpose of monitoring.

The Hall sensor is a proximity sensor with a built-in Hall integrated circuit. It uses the Hall effect to convert the presence or absence of a magnetic signal into a switch value. It is widely used in signal detection, automatic control, and safety.
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The magnetic sensor is composed of a reed switch and an amplifier. When the external magnetic field is close to the sensor, the police film is forced to magnetize and act, and then amplified by the amplifier circuit to increase the switching power to realize the on-off control of the external circuit.