Remote Controlsthe incredible saga of invisible

light

by Samuel Bradshawand Ryan Roose (of 7th)

The process, as observed

• Point a small handheld object, called a remote control, at a TV.

• Boink! At the press of a button, the TV illuminates itself!

Inside said device

Description of components

• The buttons send signals to the circuit board by pressing them.

• The circuit board receives these signals and translates them into electric pulses.

• Capacitors help by storing energy that can be used by the remote.

• The LEDs (Light-Emitting Diodes) receive electric pulses and give off light.

Behind the scenes (1/2)

• As you know, there are many kinds of light, both visible and invisible.

Behind the scenes (2/2)

• A remote control uses infrared light, which comes just after red in the electromagnetic spectrum, to send signals to the TV.

Transmitting the signal

• When a button is submitted to pressure, the circuit board transmits an electrical signal to the LEDs.

• The LEDs emit an intermittent transmission of light - all in 7-bit binary code (ones and zeros).

01000001 01100010 01101111 01110101 01110100 00100000About binary code

• Binary code uses ones and zeros to say “on” and “off” in continuous sequences at given times to make an electronic device do something.

• With the remote’s LEDs, a short beam of light represents “0”, and a long beam of light represents “1”.

• The TV then translates this binary signal into an action.

• For example, “001 0010” means “Volume up” (this can vary in different brands).

Interference?

• There are many other things that emit infrared light, from the sun to fluorescent lights (and back again).

• The TV can distinguish remote control signals from other sources because the remote control only sends a particular wavelength of infrared light (usually 980 nanometers).

A tad of history (1/2)

• The first TV remote controls were not wireless. They simply sent electric signals straight to the TV.

• Eugene Polley, an engineer, invented the first wireless TV remote in 1955.

• It was called “Flashmatic” and was essentially a flashlight that shined light on one of four photo cells around the TV screen. Each photo cell did something when light struck it.

A tad of history (2/2)

• The next development used high-frequency sounds to send a signal.

• By the early 1980s, the companies switched to infrared signals, which are what we use today.

Parenthesis: Credits• Samuel: Presentation, images, aesthetics• Ryan: Ideas, research, suggestions

</>

• http://electronics.howstuffworks.com/remote-control.htm ("How Remote Controls Work")

• http://www.zenith.com/sub_about/about_remote.html ("About Zenith")• http://www.tvhistory.tv/ ("Television History")• http://en.wikipedia.org/wiki/Light-emitting_diode ("Light-emitting diode")• http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookNERV.html

("The Nervous System")• http://www.nativevillage.org/Libraries/Media%20Library.htm ("Native

Village Media Library")• http://mathworld.wolfram.com/Binary.html ("Binary")

The End