IR Sensor

An Infrared Sensor is an electronic device, that emits in order to sense some aspects of the surroundings. It can measure the heat of an object as well as detects the motion. These types of sensors measure only infrared radiation, rather than emitting it that is called a passive IR sensor. Usually, in the infrared spectrum, all the objects radiate some form of thermal radiation.

IR technology is used in daily life and also in industries for different purposes. For example, TVs use an IR sensor to understand the signals which are transmitted from a remote control. The IR radiation in the electromagnetic spectrum can be found in the regions of the visible & microwave. Usually, the wavelengths of these waves range from 0.7 µm 5 to 1000µm. The IR spectrum can be divided into three regions like near-infrared, mid, and far-infrared.

The pyroelectric IR sensor uses a wavelength range from 2 to 14 µm. InfraTec uses special absorption layers so that the infrared sensors can even work as large-area, long-term stable receivers for UV radiation but also for THz radiation in the range of 100 µm … 1 mm. The IR radiation in the electromagnetic spectrum can be found in the regions of the visible & microwave. The main benefits of IR sensors are low power usage, their simple design & their convenient features. IR signals are not noticeable by the human eye.

Wavelength spectrum of the IR Sensor:-

  • Near IR – 0.75µm to 3 µm
  • Mid IR – 3 µm to 6 µm
  • Far IR –   > 6 µm

Terminals of IR Sensor :

  • VCC Pin is power supply input.
  • GND Pin is power supply ground.
  • OUT is an active-high o/p.
  • Distance Adjust.
  • IR Receiver.
  • IR Emitter LED.
  • Power LED.
  • Obstacle LED.

Basically, an IR LED looks like a normal LED. It has two terminals, the longer one is Positive and the smaller one is negative. When IR LED operated at a power supply, it starts emitting infrared rays. Sensor module can be powered by both 3.3V and 5V supplies.

Working of IR sensor :

The working principle of an infrared sensor is similar to the object detection sensor. This sensor includes an IR LED & an IR Photodiode, so by combining these two can be formed as a photo-coupler otherwise optocoupler. The physics laws used in this sensor are planks radiation, Stephan Boltzmann & weins displacement.

  • Planck’s Radiation Law: Any object whose temperature is not equal to absolute Zero (0 Kelvin) emits radiation.
  • Stephan Boltzmann Law: The total energy emitted at all wavelengths by a black body is related to the absolute temperature.
  • Wein’s Displacement Law: Objects of different temperature emit spectra that peak at different wavelengths that is inversely proportional to Temperature.

Features and Specifications :-

  • The operating voltage is 5VDC.
  • I/O pins – 3.3V & 5V.
  • Mounting hole.
  • The range is up to 20 cms.
  • The supply current is 20mA.
  • The range of sensing is adjustable.
  • Fixed ambient light sensor.

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