Proximity Sensor types & their applications in industries

Proximity Sensor Types and Uses in Industries

To detect the presence of an object without being into physical contact with the object, proximity sensors are used. The proximity sensor works on different principles to sense different objects. Different types of sensors are used in for different scenarios where the detection of the objects is required through non-physical contact. For example, inductive type proximity sensor used for metallic objects and capacitive type sensor for non metallic objects.

Mainly there are two types like inductive and capacitive. But proximity sensors are further classified into several types depending on the principles that are used for the detection of an object without any physical contact. They are also classified according to the type of material they sense.

Here is the list of some basic types of the proximity sensor.

Inductive Proximity Sensor:

The inductive sensor is the type of proximity sensor used to detect metallic objects without being in physical contact with the object. The principle under which the inductive proximity sensor is the electrical principle of inductance. The target object is detected when an electromagnetic force is induced in the object due to the fluctuation of the current.

The inductive sensor makes use of an oscillator circuit for the generation of the high frequency of the electromagnetic field. When an object comes in touch with the field, then at the surface of the object an eddy current will be produced. The eddy current absorbs radiated energy from the sensor, this will result in the loss of energy and also the strength of the oscillator will be changed.

inductive proximity sensor working

The changes in the strength of the magnetic field will be detected by the sensor detection section of the sensor, it will then trigger a solid-state output level if the strength of the magnetic field starts decreasing.

Advantages:

  • The accuracy rate is high
  • Switching rate is also very high 
  • Harsh environmental condition is not a limitation for this type of proximity sensor.

Disadvantages:

  • Only suitable for the detection of metallic objects
  • Range limitation

Capacitive Proximity Sensor:

Capacitive sensors are almost similar to inductive proximity sensors, the only difference between these two types of proximity sensors is that the capacitive inductor produces electrostatic instead of the electromagnetic field. 

The formation of the sensing surface is made using two metal electrodes, the oscillator produces the electrostatic field between two plates. Whenever a metallic or non-metallic object meets the electrostatic field, the capacitance of the oscillator changes. 

capacitive proximity sensor working

The oscillator circuit begins to oscillate and changes the state of the output of the proximity sensor as a result when it reaches a certain value of amplitude.

Advantages:

  • Detection of metal and non-metal object is possible with the help of capacitive sensors
  • Very high speed of detecting an object
  • Very good stability
  • Power usage is efficient 
  • The cost is very low

Disadvantages:

  • Temperature and humidity effects the performance of the sensor
  • The accuracy level is less as compared to the inductive sensor
  • Designing very difficult.
Photoelectric Proximity Sensor:

This sensor works on the principle of light for the detection of objects without any physical contact with the object. There are 2 basic types of photoelectric sensors 

  1. Reflective sensor
  2. Through-beam sensor

The reflective sensor works by the emission of a beam of light that hits the object and reflected the sensor, usually in the same physical house as beam emitter.

The through-beam sensor, on the other hand, comprises two parts, one is an emitter, also known as a source of light and the other is a detector or separate receiver. Whenever an object breaks the beam of light, the detector will register this break.

Advantages:

  • It is also known as an all-purpose sensor because it has the capability of sensing all types of material.
  • The life span is longer
  • The sensing range is good 
  • It is very reliable 
  • The response time is very fast
  • The cost is very low

Disadvantages:

  • Lens gets contaminated 
  • Two separate components are required.

All the different proximity sensors types and their application in industries are well described and their comparison you can see in following image

Proximity sensor types

If you want to learn about working principles for all above sensors you can check this link

All images credit goes to machinedesign

What is Proximity Sensor in Mobile

What are Proximity Sensors

As the sensor name suggest, Proximity sensor is a sensor which can detect other object, which comes closer to it, up to a certain range of distance without any physical connection. The covering distance of sensor is called sensing range which varies according to size of sensor, for example an 18 mm diameter inductive sensor will have sensing range for 5 mm to 8 mm. See datasheet here so you can get idea that what is proximity sensor.

The maximum distance at which sensor can sense other object is called nominal range, which is also depend on size of sensors. There are some sensors for which you can adjust their sensing and nominal ranges. You can see here how adjustable proximity sensor works. Proximity sensor are highly reliable and long functional life because of no mechanical parts and no physical contact between sensor and sensed object.

How it works

Proximity sensor emits electromagnetic field or a ray of electromagnetic radiations, infrared, for instance, and wait for changes in these radiations or bounce back signal. The object which is sensed by proximity sensor is often called sensor’s target object. The target demand for different proximity sensors is different. For example , a capacitive proximity sensor or photoelectric sensor often demands for plastic target which is more suitable for them and an inductive proximity sensor always want a metal object as sensor’s target.

Proximity sensor working
proximity sensor working

Proximity sensor types

There are different types of proximity sensors but mainly are two by which they known.

  1. Inductive type
  2. Capacitive type

Inductive type can detect metal objects and capacitive type can detect any object which come closer to them. If you want to check other types you can view by this link.

Proximity sensor uses

Proximity sensors have huge applications across every technological field. They finds application in industrial and manufacturing areas. They sense material and then response some type of action or simply tell about presence or absence of that material. The most important feature of these sensor is that they don’t require physical connection with their target which is being sensed. That is why they are often called non-contact sensors.

Every type of sensor has its own technique of use for a specific operation in any device. Here I will tell you about the applications of proximity sensors in android and IOS.

what is proximity sensor in mobile

I hope now you are known by this fact that proximity sensor works when anything come close to it. Here i will tell you about working of proximity sensor in mobile.

Large touch screen displays use huge battery power. So it should be turned off while you its not in use like calling someone or when the phone is in pocket. In that case proximity sensor turn off your mobile screen, as in both case mobile screen is close to your ear/cheeks or body in pocket. In such cases proximity sensor activate, sense object and send a signal to mobile processor to turn off display.

There are some other methods also, that are used for proximity sensing. For example, detecting the change in capacitance, inductance, magnetic field or even techniques like sonar. But, I doubt if they are used in mobiles. Thank you for your reading.

Please feel free to ask me anything about it.