March 17, 2019
We encounter infrared technology everyday via remote control devices that we use with our TVs. For the most part, these remotes use infrared light to transmit signals, but some use radio waves.
Aside from your TV remote, infrared is used by the military, law enforcement and for many industrial applications. For those who are curious about how infrared devices work, here is a brief overview.
What is “infrared”?
Infrared (IR) is a type of electromagnetic radiation (EMR). That might sound dangerous, but it’s actually less harmful than normal visible light. All types of light are radiation.
Infrared light has a longer wavelength than visible light and a lower frequency. Because of this, it is invisible to the human eye. However, there are some special cases involving pulsed IR lasers that are visible to humans. Objects that are near room temperature or slightly warmer emit infrared light. This is why special night vision equipment allows people to see many objects in a completely dark environment.
How remote controls work
A remote control sends out binary code to a device with pulses of infrared light. Binary code is basically a combination of zeroes and ones that the computer chip in the device can interpret as instructions via machine binary language.
The anatomy of the remote control consists of buttons, integrated circuits, button contacts and a light emitting diode (LED). There are many other parts, but these are the most crucial ones to understand the functioning of the device.
In order for the remote to work, the TV needs to have a receiver in front of it that picks up the infrared signal. The remote usually only works when you point it at the TV. This is because it’s sending a beam of invisible light that has to have a clear line of sight in order for the TV to receive it.
This is unlike radio waves that are capable of passing through objects and contacting the receiver. Some IR remotes have a strong enough pulse that you don’t have to point them exactly at the TV because some of the scattering light will also get picked up by the receiver.
The process that happens when you use the remote is as follows. First, you push a button on the remote, which causes it to connect with the contact underneath. This completes a circuit that transmits a binary signal to perform the action that the button specifies, such as turning the volume up. The command is translated into a digital communication that is emitted from the LED at the top of the remote and travels through the air to the receiver on the TV.
Without getting too technical, this is basically how IR equipment works. For a deeper understanding, you probably need an engineering degree. Next time you’re with friends, you should be able to explain to them why they need to point it at the TV to turn it on.