What is a proximity sensor?
Proximity sensors can replace mechanical switches such as limit switches or micro switches, and can detect the proximity of detected objects without contact.

Detection principle:
Due to the use of detection coils, high-frequency magnetic fields will occur. According to electromagnetic induction, if the detected object (metal) is brought close to the magnetic field, induced current (eddy current) will flow in the detected object. In this current, if the obstruction of the detection coil changes, detection can be performed by stopping oscillation.

Proximity sensors are divided into shielded and unshielded types. Shielded sensors can also be referred to as buried or flush sensors, while unshielded sensors can be referred to as non buried or non flush sensors.
The shielded magnetic flux is concentrated in the front of the sensor, and the range of its inductive magnetic field is towards the front of the proximity switch.
Non shielded coil magnetic flux protrusion can increase the detection distance, but it is easily affected by surrounding metals due to the lack of object protection.

Below is a detailed explanation of the main differences between shielded and unshielded types:

Appearance difference
The side of the shielded detection coil is covered with metal and can be embedded in metal for use.

The side of the unshielded detection coil is not covered with metal.

Installation difference
Shielded products can be installed flat with the metal mounting surface without being affected.
For unshielded products, the detection surface must be a certain distance higher than the metal installation surface, otherwise signal errors may occur.

Detection distance
The detection distance for products of the same size is relatively close for shielded products and relatively far for unshielded products.