Principle and characteristics of IFM capacitive sensors

Create Date: 2024-8-30 12:03:23|Source: IFM/ifm

Capacitive sensors can detect any object without touch. In contrast to inductive sensors, which can only detect metals, capacitive sensors are also capable of detecting non-metallic materials.

Principle and characteristics of IFM capacitive sensors

Principle and characteristics of IFM capacitive sensors

principle

1. The first thing is to measure the capacitance between the sensor sensing surface electrode and the circuit potential electrode, a close object will affect the electric field between the two poles of the capacitor. Principle 1 is only applicable to metal objects and also applies to non-metal objects.

2. In principle, capacitive sensors operate with an RC oscillator, and even a small capacitance change will affect its amplitude. The integrated processing display then converts the amplitude into a switching signal. Its sensitivity can be conditioned by a potentiometer.

Enhanced immunity to interference

1. When detecting an object, the capacitance as small as 0.02pF must be changed (the basic capacitance of an electrode is at least 0.pF!). ) is accurately converted into a usable switching signal. This places high demands on the circuit, as the basic capacitance required by the circuit and structure (e.g., the input capacitance of conductor circuits and components) is increased many times, which greatly increases the difficulty of accurate capacitance detection.

2. In this regard, ifm electronics has developed a forward-looking plan to deal with this problem. A new sensor circuit design is designed to be very effective in avoiding the problems presented by the RC oscillator described earlier. The new circuit plan significantly obtains better values for anti-interference parameters.

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