There are a lot of sensors that you come across in your daily life. And one of them is the Proximity sensor. You might have used them many times without even knowing about it. These sensors alert you when you get close to something. You can’t just walk past something without activating or detecting it. These sensors can sense your presence and react accordingly.
Besides being used in smartphones, proximity sensors are used in a lot of other products and household appliances. They are used to detect the user when they are getting close. And these sensors alert you when you need to take some precautions.
For example, if you are going to get too close to an electronic device, or a metallic object. We are going to discuss everything you need to know about proximity sensors in this article.
What is a proximity sensor?
A proximity sensor is a device that is used to detect the presence of an object in close proximity. It is designed to detect the presence or absence of an object without deploying physical touch.
They are used to detect the presence of objects or people from a distance. They can be used to sense the presence of an object near a surface or close to a surface.
The proximity sensor is very sensitive and is designed in such a way that it can detect an object even when it is very close.
They are also designed in such a way that they can detect the absence of an object when it is not there.
Proximity sensors come in all shapes and sizes. They are available in various types and designs depending on the requirements of the product they are going to be used. They come with different features as per their application and usage.
Operating principle of proximity sensors
How does a proximity sensor work?
From the definition, we have stated that the general working of a proximity sensor is detecting the presence or absence of an object and then sending the relevant data.
But how does this happen?
Since there are different variants of proximity sensors, their operation principle is not all the same. The main principles behind the working of the proximity sensors.
Inductive proximity sensor
Inductive proximity sensors are designed to detect the magnetic loss due to the effects of eddy currents being generated on a conductive surface by another external magnetic field.
A detection coil generates the AC magnetic field. This field tends to change the impedance due to the effects of the eddy currents that are generated by the metal object being detected.
As you can tell, the inductive proximity sensor is perfect for detecting metal objects.
Under this working principle, we have an aluminum-detecting sensor technology that works using the same principle.
Two other common sensors that tend to ride on this principle include All-metal sensors and Pulse-response sensors.
Principle of a capacitive proximity sensor
This type of proximity sensor detects the differential capacitance between the object and the sensing object. The sensing object is the metal plate that is separated from the metal object to be detected by a small gap.
The metal plate and the metal object are usually made of different materials, with different dielectric constants.
The capacitance will be different between them because one is made of a material with a high dielectric constant while the other one is made of a material with a low dielectric constant. The capacitive proximity sensor operates in an active mode: it generates an alternating current in the air and measures its frequency.
When there is an object near to it, this frequency decreases because the capacitance has increased. This can be done by using two identical coils, each one excited by a sinusoidal signal generator. The signals are then added together and measured on an oscilloscope.
Since the amplitude of both signals decreases when there is an obstacle in front of them, their sum will also decrease when there is something in front of them. Capacitive sensors have high sensitivity and a wide frequency response range. They can also easily be used in high-speed applications.
Principle of the magnetic proximity sensor
The working principle of this type of proximity sensor is quite straightforward. As the name suggests, it uses a magnet to sense an object. The reed end of the sensing equipment has a magnet. It also has a switch that you can turn ON and OFF.
When the magnet is far away from any object, the magnet will attract the magnetic field lines. And when the magnet gets closer to an object, the magnetic field lines will be disrupted and an ON signal is generated.
When the magnet moves away from an object, it generates an OFF signal. The reason why a magnetic proximity sensor works better than a capacitive sensor is that it has a higher inductance and a wider frequency response range.
Principle of an ultrasonic proximity sensor
This is another type of proximity sensor that is commonly used. It works by emitting a high-frequency sound wave and measuring the distance to objects. The emitted sound waves will bounce off of an object and then return back to the sensor. The frequency of the sound wave is measured and converted into an electrical signal.
These sensors work by sending out an infrared beam, which is reflected off of any object that has been placed in front of them. The frequency at which the beam is emitted can be adjusted to determine if there are any obstacles in front of the sensor. The time between when the beam hits an object and when it returns back to the sensor can then be measured and converted into a voltage signal. This voltage signal is then processed by a microcontroller, which turns it into a digital signal that can be interpreted by software or hardware as a “proximity” event.
Features of proximity sensors
Regardless of the type or the operation technology, here are the notable features of proximity sensors:
By contactless, we simply mean the ability of an object to sense without physically touching the object. The object being sensed will remain intact, without any blemish or contamination.
Rapid response time
The response time of the proximity sensor is very fast. It takes only a few microseconds for the sensor to sense an object. And it takes even less time for the output to change state.
No mechanical wear or tear
The proximity sensor is a non-contact type. Therefore, there won’t be any wear and tear on the object being sensed.
Easy to integrate into the control system
Proximity sensors can be easily integrated into the control system by using a few I/O pins of the microcontroller. It doesn’t require any special hardware or software setup to run it.
Accurate and reliable
Proximity sensors are normally reliable and accurate. There are no moving parts to wear out or cause any inaccuracy in sensing.
No component alignment required
Proximity sensors work by measuring the field intensity. Therefore there is no need for component alignment, unlike other sensor types. The sensor will detect the presence of an object regardless of its size, shape, or orientation.
Suitable for a wide range of applications
The proximity sensor is very useful in detecting the presence of a wide range of objects. For example, it can detect the presence of a person in a room, or even an animal or insect. It can also be used to sense the presence of an object on a conveyor belt or rail, for example.
Can detect objects with different sizes and shapes
The proximity sensor can detect objects of different sizes, shapes, and materials. It is also very sensitive to touch. Objects that are hard to detect by other sensors (such as thin wires) can be detected properly.
Not affected by water and fluids
Unlike the optical sensors, proximity sensors are not affected by water or liquids. This makes the sensor suitable for use in harsh environments such as underwater, underwater, and when working in gaseous environments.
Easy to install and use
Installation is easy and requires no special tools. The sensor can be installed on a wide range of surfaces, such as walls, railings, floors, ceilings, and doors. It can also be used on the interior of a vehicle.
Not affected by temperature
So you want a robust sensor whose performance won’t be affected by the surrounding conditions? Proximity sensors may be your go-to solution. The working, accuracy, and performance of these sensors are not affected by the temperature. They can be used even in the harshest weather conditions.
Low energy consumption
Proximity sensors consume very low power when in standby mode, but inactive mode they consume more power than other types of sensors. Proximity sensors are suitable for most applications where low power consumption is important.
Applications of proximity sensors
Here are the most common application areas of the proximity sensors:
Modern proximity sensors can measure distance in an accurate and precise manner. The sensor can measure the distance between two objects and detect when the object is too close or too far away.
The proximity sensors can sense when an object is moving within the range of their detection. It is used in applications such as automatic doors, security systems, or power-saving devices.
The proximity sensors can be used for controlling access to rooms or areas where people are not supposed to enter.
For robotics, the proximity sensor can be used to determine how far away an object is from a robot so that it can manipulate the object accordingly. This can be used for many purposes such as picking up objects, opening doors, and operating machinery.
Unmanned aerial vehicles (UAV)
UAVs are autonomous aerial vehicles that are used to conduct reconnaissance, surveillance, and communications. The proximity sensor is used to determine the distance between the UAV and any object to prevent collision with the object.
Automation in the production process
The proximity sensor is used in automated machinery to determine when an object is too close to the machinery so that the machinery can be stopped or slowed down.
What to look for when buying proximity sensors
Here are the key things to look out for when buying proximity sensors
-Application area: Where do you intend to use the proximity sensor? Is it for indoor or outdoor use?
-Contact type: Do you need the proximity sensor to be connected to a contact relay? If so, what are the kind of contacts you need (e.g., spring-loaded, screw terminals)?
-Shielding: Does the proximity sensor require a shield? If so, is it required in all directions or only in one direction (e.g., to protect the sensor from electromagnetic interference)? Also note that shields are not always necessary as some sensors can be used without them (e.g., ultrasonic sensors).
-Installation mode (Flush or non-flush): Is the proximity sensor mounted flush with the surface or in a recess?
-Mounting options: Do you need a mounting plate for your proximity sensor? Is it necessary to mount your proximity sensor on top of a plate or can you mount it directly onto the surface?
-Specifications: What are the requirements for your proximity sensor (e.g., operating temperature range)? Does it have to be able to withstand high temperatures? And if so, how much (e.g., 10,000 hours)?
-Electrical characteristics: What are the operating voltage and current ratings of your proximity sensor? Also note that some sensors may require an external power supply (e.g., 250 VAC or 12 VDC).
-Response time: How fast does your proximity sensor need to respond?
-Range: How far can the sensor detect objects (e.g., inches or feet)? Are there any requirements for the maximum distance (e.g., 50 cm or 2 ft)?
-Sensitivity: How sensitive is your proximity sensor to objects (e.g., if it can detect a 0.5 mm object, then it should be able to detect a 1 mm object)? Also, note that some sensors may be more sensitive than others.
I hope that now you have adequate information about proximity sensors. As a sourcing agent, we can help you acquire proximity sensors in China. If you have any questions, please feel free to contact ICRFQ.
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