Information About Proximity Sensors

Proximity Sensor

  • A proximity sensor is a device which detects objects when they get within a certain distance from the sensor. The proximity sensor will then usually send a signal to an electronic circuit to perform a simple action, such as opening a door, turning on a light or sounding an alarm Many proximity circuits detect anything that comes too close. Others are designed to pick up on a particular type of object and ignore everything else. Proximity switches are devices which detect when an object is nearby. When an object gets within a certain distance, they will turn on a circuit to perform some basic function, such as opening a door or turning on a light or an alarm. Some proximity switches are designed to detect certain kinds of objects, while others will detect pretty much anything.

Active Proximity Sensors

  • Active proximity sensors actively hunt for an object. They typically send out some sort of signal and wait for it to be reflected back. By measuring the time between sending the signal and getting a reflection, they can determine how far away the nearest object is. For example, the proximity sensors on automatic doors send beams of infrared light out at an angle that will intercept anyone walking within a few feet of them. When someone walks up to the door, the light bounces off of him and back to the sensor. The sensor then tells the door to open.

Passive Proximity Sensors

  • Passive proximity switches work by absorbing information from their environment. When a particular change occurs, they note the change, and send a signal to a circuit. For example, outdoor safety lights use a carefully tuned infrared sensor to look for people. Everything emits infrared light, but the frequency of the light depends on the object. The human body emits a particular frequency which the sensor is tuned to recognize. When it registers that frequency of infrared, the sensor turns on the light.

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 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 always 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. 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. International Electrotechnical Commission (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.   Other Models…   Need More Information:

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20th Jan 2015

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