The electronic devices used to detect the object regardless of the material or the state of its physical form without making direct contact with it are known as capacitive sensors.
It detects the objects using their electrical field effect formed by the sensor as it comes in the range of the sensor and interrupts the electrical field.
Working of Capacitive Sensor
A capacitive sensor works similarly to a regular capacitor, a metal plate is internally connected electrically to the oscillator circuit and the other plate is formed by the object that has to be detected and an electrostatic field is generated.
The block diagram of the capacitive sensor is shown above. It consists of a high-frequency oscillator, with a sensing surface that is formed through two metal electrodes. Consequently, the oscillator circuit will begin to oscillate & change the sensor’s output condition once it arrives at a certain amplitude.
Once the target goes away from the capacitive sensor, the amplitude of the oscillator will reduce, switching the capacitive sensor back to its original position.
This sensor’s typical detecting range is about 1 inch or 25 mm whereas some sensors’ range is extended up to 2 inches.
These sensors detect the superior dielectric constant of an object simply. So, this makes achievable the detection of the material within nonmetallic containers because the dielectric constant of liquid is much higher as compared to the container. So this provides the sensor ability to observe throughout the container & detect the liquid. For better operation, they must utilize in a situation with a quite constant temperature & humidity.
Applications of Capacitive Sensor
They can also be used for counting and checking liquid levels.
When these sensors are used for part detection, the sensor just sends a signal to the workstation, conveyor, or robot so they know when the part is there.
A capacitive sensor can be set up on a conveyor to trigger a counter so that it can count how many parts have been built.
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