Why do remote controls use infrared light instead of other wavelengths?
In: Technology
The remote control is actually a pretty bright blinking light. People hate bright blinking lights, especially in very dark rooms. By using infrared, the light can be bright, yet invisible to human perception.
Infrared can also use a black piece of plastic for filter out visible light, while passing the infrared light through it, as if it were clear, so noise can be filtered out.
It’s cheaper and easier. For infrared you need an infrared diode on the transmitter, and an infrared receiver on the TV. Cheap and easily available parts. For a radio, you would need an oscillator, modulator circuit, and antenna on the transmitter, and a antenna and receiver/demodulator circuit on the TV. More parts, which translates to more expense. The cheaper solution works for the required application, so that’s what they go with.
I know right? Emitting small amounts of gamma radiation should be harmless.
All those IR remote controls use an LED (light-emitting diode) as the light. As it turns out, the first LEDs created were red LEDs, followed by yellow, green and only much more recently blue. So the original choices were really only red or infra-red. Of the two, infra-red has the advantage that it looks more magical: you press a button, can’t see what’s going on, and shazam! your TV changes channel.
At this point, infra-red has the advantage that it’s cheap and well-understood: you can buy essentially “kits” for your product to make your remote.
TL/DR: infra-red was available and cheap. Other colors, not so much.
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