A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact. A proximity sensor often emits an electromagnetic or electrostatic 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 or photoelectric sensor might be suitable for a plastic target; an inductive proximity sensor requires a metal target.
The maximum distance that this sensor can detect is defined "nominal range". Some sensors have adjustments of the nominal range or means to report a graduated detection distance.
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object. IEC 60947-5-2 defines the technical details of proximity sensors. A proximity sensor adjusted to a very short range is often used as a touch switch. A proximity sensor is divided in two halves and if the two halves move away from each other, then a signal is activated. A proximity sensor can be used in windows, and the window opens an alarm is activated.
Types of Proximity sensor
- Car bumpers that sense distance to nearby cars for parking
- Ground proximity warning system for aviation safety
- Vibration | Position measurements of rotating shafts in machinery
- Sheet break sensing in paper machine.
- Anti-aircraft artillery
- Mobile Phones
Electrical sensors examine the change in electrical or magnetic signals based on an environmental input.Examples of electrical sensors are metal detectors, RADAR systems and even simple electrical meters such as voltmeters and ohmmeters. Magnetometers are widely used in traffic intersections to detect the presence of a vehicle.