Video displays are both getting bigger and also getting thinner, as increasingly complex and detailed technologies are implemented to ensure advertising screens are as bright as possible.
All of this is possible thanks to a range of technological developments, chief among which is the liquid crystal display (LCD), which have a much longer history than you would expect.
Interestingly enough, this history also involves experiments using carrots.
What Is A Liquid Crystal?
Making an LCD is complex, but at the core of it is the liquid crystals that give the LCD most of its name.
Liquid crystals are interesting as they are not a particular material but a state of matter between a solid and a liquid. Liquid crystal molecules move around to different position but tend to stay in the same orientation. These unique qualities make every other part of an LCD screen possible.
The phenomenon was discovered largely by accident by Austrian botanist Friedrich Richard Reinitzer, who had extracted cholesterol from carrots, and through experimentation found it had some rather bizarre properties.
Essentially the cholesterol had two melting points, a state between solid and liquid, which became known as liquid crystal. He also found that when it was cooled at specific temperatures it would change colours.
He presented his findings to the Vienna Chemical Society in 1888 and whilst they were impressed, they did not have any real use for the technology, so the interest dropped after Otto Lehmann detailed the bizarre phenomenon.
It would take until 1936 for any real attempt to use the technology to be found, with the first patent for a practical use for the technology being made by the Marconi Wireless Telegraph Company.
From Carrots To Computer Screens
Developing the technology behind LCDs was a long process, as several parts are needed to make an LCD work.
Liquid crystals transmit and change any light that has been polarised, which is where light waves are forced to travel in a certain direction.
You also need liquid crystals that change their molecular structure when passed through an electric current, which typically changes them from a naturally twisted to an untwisted state, depending on the voltage.
Finally, you need a transparent substance that can conduct electricity to avoid any loss of light.
So to make a simple LCD screen, you get two polarised glass surfaces, place the polarising film on one glass surface and have grooves on the other in the same direction.
Then you add a coating of twisted (or nematic) liquid crystals that align in the same direction as the first layer of glass, before adding the other layer at a right angle.
How this works is that the light is polarised when it goes through the first piece of glass, directing it into the liquid crystal later, which bends the light to allow it to pass through the second layer.
If an electrical current is passed through, these liquid crystals untwist and do not pass through into the other layer, which makes the pixel dark.
Do this for every one of the millions of pixels on a modern screen, add a light source and you have an LCD screen.