What is a proximity sensor?
Seemingly ordinary proximity sensors, in fact, there is a lot to be said for the correct selection and use, to enhance the reliability and stability of your equipment is essential.

The detection method that converts to electrical signals, includes the method that utilizes the eddy current generated in the metal body of the detection object caused by electromagnetic induction, the method that captures the change in the capacity of the electrical signal caused by the proximity of the measurement body, and the method of the lithium and the guided switch. It consists of inductive type, electrostatic capacity type, ultrasonic type, photoelectric type, magnetic type, and so on.
Proximity sensor is a general term for sensors that are used to detect objects without contacting them and to replace contact detection methods such as limit switches. It has the ability to convert observed information about the motion and presence of an object into electrical impulses.

What are the advantages of proximity sensors?
① The thing to be detected will not be worn or damaged as it may be detected without contact.
② Life extension due to non-contact output method (except magnetic type) Semiconductor output is adopted, which does not affect contact life.
③ It is suitable for use in conditions such as water and oil, and unlike the optical detection method, it is not affected by stains, oil, or water of the item to be detected. In addition, there are also products with Teflon housings and high chemical resistance.
④ High-speed response is possible compared to contact switches.
⑤ Can withstand a wide temperature range.
⑥ No effect on the color of the object to be detected: Since changes in the physical properties of the object to be detected are detected, the color of the surface is hardly affected.
⑦ It will be affected by the surrounding temperature, surrounding objects, and sensors of the same type, such as inductive and electrostatic capacitive sensors, which affect each other, unlike the contact type. Therefore, mutual interference must be addressed when setting up sensors. In addition, inductive types must consider the effects of surrounding metals, while electrostatic capacitive types must consider the effects of surrounding objects.
When a metal detector is close to the sensing area of the sensor, the switch can be operated without contact, pressure, or sparks, and quickly sends out an electrical signal that accurately reflects the position and travel of the moving mechanism. Even when used for general travel control, its positioning accuracy, operating frequency, service life, ease of installation and adjustment, and ability to adapt to harsh conditions make it unrivaled.

Product classification:
(1) Proximity sensors are categorized according to the principle of operation.
High-frequency oscillation type
Capacitive
Induction bridge type
Permanent magnet type
Hall effect type 

(2) They can be categorized according to the principle of operation:
High-frequency oscillation type using electromagnetic induction
Magnetic type utilizing a magnet
Capacitance type utilizing capacitance change

(3) Divided by detection method:
General-purpose type: mainly detects ferrous metals (iron)
All-metal type: Detects any metal within the same detection distance.
Non-ferrous metal type: mainly detects non-ferrous metals such as aluminum

(4) According to the structure type.
Two-wire type: easy wiring, but there are residual voltage and leakage current drawbacks
Three-wire type: DC three-wire proximity sensor output type NPN