How Proximity Sensors Work


Proximity sensors are devices that many people come across every day without even realizing it. With a variety of applications, proximity sensors can detect the presence of an object without actually coming into contact with it. Because of how useful a function this is, one can imagine all the applications that such sensors can have.

If you have ever washed your hands under a motion-activated faucet, then you have very likely used a proximity sensor. If you drive a car with parking sensors, then your vehicle is equipped with proximity sensors. Some roller coasters even have these sensors included in their mechanics as well.

With so many applications, you might very well be wondering just how these sensors work. A marvel of modern engineering, the way in which these devises work isn’t too terribly complicated to comprehend.

What’s the Target?

There are a few different ways that proximity sensors work. The type of sensor that you encounter will depend on what sort of target it was designed to respond to. The target of a proximity sensor is the object that the device detects. Since the target will be made from a particular material, the sensor will need to emit an electromagnetic beam that can detect that material.

If the target is made from plastic, for instance, the proximity sensor will send out infrared light that will bounce off the target back to a photoelectric receiver. Such a sensor is referred to as a photoelectric sensor. Another target, such as metal or a living person, might require a different sort of electromagnetic beam to be detected by the sensor.

Common Types of Sensors

While there is a significant number of proximity sensors out there with a variety of applications, there are a few that are more commonly seen in daily life than others. Such sensors include inductive sensors, capacitive sensors, ultrasonic sensors, and infrared sensors (such as in the example above). Although differing in some key areas, each of these will share some commonality in the features they possess.

Naturally, each of these proximity sensors will be able to perform contactless detection on their designated target type. They will also each only be able to detect the true physical nature of a target. This means that it doesn’t matter what color or size the target is. So long as it is comprised of the designated material, the proximity sensor will be able to detect it.

Proximity sensors also provide a high response rate, with reaction times in some cases being nearly immediate. You might have noticed this with the example of the motion-activated faucet. Some models will be sensitive enough to turn on the tap almost instantly.

These types of sensors typically have a longer lifespan than other, more traditional sensors. This is a result of the fact that one doesn’t have to come into contact with them in order to use them. Less wear and tear means a longer life. They also don’t have any moving parts internally, a fact that further reduces the wearing down of internal mechanisms.


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