The Chemistry of LCD Monitors


YouTube Video

Well after starting the research for monitors I realized that I needed to focus on one single type of monitor and the one I chose was LCD monitors.  LCD stands for Liquid Crystal Display.  A LCD is a monitor that was made to replace the CRT (Cathode Ray Tube).  The reason CRTs needed to be replaced was because they are those bulky tube tvs that take up an enormous amount of room.  I chose to do research on monitors (or well in this case LCDs) because in the modern world you can hardly find a building that doesn’t have a single display of some kind inside so I thought it would be interesting to find out how they work.  LCDs haven’t specifically changed how I live it’s more of a general usage of monitors/displays.  Everywhere you go now you can probably find a screen or monitor of some type. So it’s not really my life that they are directly affecting,  it’s our world as a whole that is impacted by it.

Composition of ...

  • Thin-film transistor

    • Borosilicate glass (~13%B2O3 + ~80%SiO2)

  • Electrode Pattern

    • (Cu, Ti, CF4, SF6, He, N)

  • Liquid crystal

    • (C41H72O2)

  • Polarizer

    • (AgBr, C6H4(OH)2, K2O3S2, KOH

Main Chemicals, Compounds, Components

Liquid Crystal :

Liquid crystal is a state of matter that has a crystal-like molecular structure.  It allows light to pass through when it needs to and when it doesn’t it blocks the light.  It is good for displays because in the liquid crystal state light gets organized from the liquid crystal and prints out a very crisp looking picture.  It was first discovered in 1888 by Friedrich Reinitzer.  The first time liquid crystal was used in displays was in 1962.  The reason that liquid crystal is used in displays is because it allows the monitor to be thinner compared to CRTs (those big bulky “old school” tvs).  It is allowed to be thinner because instead of projecting light onto the screen it just organizes light that is already there.  Another reason it is used in displays is because it requires less power to run than a CRT.  You can find Liquid crystal in Liquid Crystal Displays or LCDs.  

Polarizer :

Polarizers work by only allowing light that is moving the same way that it is made. So only vertical light can go through vertical polarizers and vice versa for horizontal polarizers. Polarizers are basically a very small grid that is used for cameras and displays.  They are very good at lining up light and giving smooth results.  They were first developed in 1929 by Edwin H. Land. Their main purpose is for cameras when they were first invented but now they are used in displays also. The reason that they are more commonly used in displays now is because they require less power to run.  Instead of turning light on and off inside of a monitor, they just line up the light that is already there.  It is a perfect for liquid crystal displays because when the light passes through the liquid crystal it flips it 90 degrees so it can go through the second polarizer.  Always in LCDs the polarizers are 90 degrees of each other.

Chemistry's Role

Liquid crystal composite :

liquid crystals can be man made and they can also be apart of nature.  One example of liquid crystal in nature is spider webs.  When they push it out, the silk is liquidy but it then turns into a solid.  An example of a lab made liquid crystal is Vanadium(V) oxide.  It is made by taking a vanadium rich ore and is mixed with Na2CO3.  This produces NaVO3.  The ph is raised on this to about 2 to 3 using H2SO4.  This creates a precipitate which is heated to 690 oC which gives the final product V2O5.  The chemistry involved with liquid crystal is using the proper amount of heat/electricity to get the liquid crystal state.

Polarizer composite :

Polarizers were originally made of microscopic herapathite crystals but now they are made of polyvinyl alcohol plastic with iodine doping.  With polarizers, the chemistry is all about allowing light to pass through and reflecting light that isn’t aligned with it.  If the polarizer is off centered or isn’t rotated 90 degrees to the other one there will be a blurry if not black picture.  

Background Research

One important thing to know to help understand how computer monitors work is light polarization.  

-Unpolarized light is light that is free roaming light that goes in any direction much like the sun.

-Polarized light is light that is focused into a single path much like a laser.

Liquid crystal is a substance that moves like a liquid but has a crystal-like molecular build up which allows light to pass through.



About the Author
I little bit about Jordan.  He enjoys his fare share of memes and also enjoys to learn a thing or two every now and then.  One of his major interest is the study of matter, or better known as Chemistry.  Although he would like to go to college for Chemistry he is choosing to go for an Accounting major.  He is going to do his generals at MSU-B then look for another college to begin studying for his accounting major.  He has gone 2.5 years of high school with a 4.0 GPA and perfect attendance and he isn’t slowing down anytime soon.  He is hoping to make it all 4 years because it is a personal goal of his.