Proximity sensor; types and applications

The proximity sensor is another type of contactless sensors that detect the presence, movement and closeness of an object.

Basically, it mesures the proximity or closeness of an object to it, by emitting high frequency electromagnetic field ( Ultrasonic sound is a type of electromagnetic wave) in form of ultrasonic sound (its an inuadible sound because of it's high frequency) to an object 

A proximity sensor often emits an electromagnetic field or a beam of electromagnetic radiation (infrared, for instance), and looks for changes in the field or return signal. The object being sensed is often referred to as the proximity sensor's target. Different proximity sensor targets demand different sensors. For example, a capacitive proximity sensor or photoelectric sensor might be suitable for a plastic target; an inductive proximity sensor always requires a metal target.

Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between the sensor and the sensed object. Proximity sensors are also used in machine vibration monitoring to measure the variation in distance between a shaft and its support bearing. This is common in large steam turbines, compressors, and motors that use sleeve-type bearings. A proximity sensor adjusted to a very short range is often used as a touch switch.

Types of proximity sensors.

1. Inductive proximity sensors. 
2.  Optical Proximity Sensor.
3. Capacitive Proximity Sensor. 
4. Magnetic Proximity Sensor. 
5. Ultrasonic proximity Sensor. 

Applications of proximity sensors.

1. Object detection
2.  Counting of pieces 
3. Velocity measurements Rotation 
4. Positioning objects / containers
5.  Detection of materials  
6. Determine the direction of movement 
7. Monitoring of tools 
8.  Detection of liquid levels 
9. Distance measuring Machine 
10. Protection Edge detection of an object 
11. Gear Checking Detection of metal objects
12. Positioning fork lift truck 
13. Positioning of equipment in stock
14. Detection and filling quantities Obstacle detection