Capacitive proximity sensors can be used to detect metallic and also non metallic targets like paper, wood, plastic, glass, wood, powder, liquid..etc without physical contact. The capacitive proximity sensor works on the capacitor principle. The main components of the capacitive proximity sensor are plate, oscillator, threshold detector and the output circuit.
The plate inside the sensor acts as one plate of the capacitor and the target acts as another plate and the air acts as the dielectric between the plates.
As the object comes close to the plate of the capacitor the capacitance increases and as the object moves away the capacitance decreases. The detector circuit checks the amplitude output from the oscillator and based on that the output switches.
The capacitive sensor can detect any targets whose dielectric constant is more than air
The advantages of capacitive sensor are
The plate inside the sensor acts as one plate of the capacitor and the target acts as another plate and the air acts as the dielectric between the plates.
As the object comes close to the plate of the capacitor the capacitance increases and as the object moves away the capacitance decreases. The detector circuit checks the amplitude output from the oscillator and based on that the output switches.
The capacitive sensor can detect any targets whose dielectric constant is more than air
The advantages of capacitive sensor are
- It can detect both metallic and non metallic targets.
- Good stability
- High Speed
- Good Resolution
- Capacitive sensors are good in terms of power usage
- Low cost
- They are affected by temperature and humidity
- Could be triggered by dust, moisture..etc
- Sensitive to noise
- Difficulties in designing
- Linearity is not good
- Capacitive proximity sensors are not as accurate compare to inductive sensors.
- Proximity Detection
