A proximity sensor is a device that senses or detects the presence of a nearby object without any physical contact. A proximity sensor emits electromagnetic radiation such as infrared and looks for changes in the field or return signal. The object being sensed is often referred to as the proximity sensor targets demand different sensors. For example such as a capacitive proximity sensor or photoelectric sensor might be suitable for a plastic target. An inductive proximity sensor always requires a metal target.
Thus proximity sensor can have high reliability and long functional life because of the absence of mechanical parts of physical contact between the sensor and the object which is to be sensed. Proximity sensors are also used in machine vibration monitoring to measure the variation in distance between the shaft and its support bearing. This is very common in large steam turbines, compressors, and motors that use sleeve-type bearings.
Types of sensor
- Capacitive displacement sensor
- Doppler effect
- Magnetic, including magnetic proximity fuse
- Optical sensors such as a photoelectric, photocell, etc.
- Reflection of ionizing radiation
- Sonar which is typically active or passive
- Ultrasonic sensor
- Fiber optics sensor
- Hall effect sensor
- Parking sensor, as the system mounted on car bumpers that sense the distance to nearby cars for parking
- Inductive sensor
- Ground proximity warning system for aviation safety purposes.
- Vibration measurement of rotating shafts in machinery
- Anti-aircraft warfare
- Roller coasters
- Conveyor system
- Mobile device