Display Technologies Part IV: Flat Panel LCD

By Lancelot Braithwaite
Sept Issue; Widescreen Review

About 5000 BC the best humans could do was use logs under sleds to move heavy loads. It took about 1,500 years before it became a recognizable wheel. The development of  iquid crystal technology has taken only 150 years from its first observation to the large liquid crystal displays (LCDs) of today.

In the 1850s, Rudolf Virchow, C. Mettenheimer, and Gabriel Gustav Valentin found that the nerve fiber they were studying formed a liquid substance when left in water that exhibited strange behavior when viewed using polarized light; they didn’t know it, but they were observing liquid crystals. At that time, matter was only supposed to be in three forms: solid, liquid, and gas. Solids had molecules with an organized, ordered crystalline structure, liquids had molecules with a disorganized structure, and gasses had molecules with no structural identity. Even after liquid crystals were formally “discovered” in 1888, it took until the 1920s before scientists accepted the fact that matter could assume more than three states. Liquid crystals are matter in the state of melting from a solid into a liquid. With many solids there is a short range of temperature at which the change from solid to liquid takes place. However, for some solids that change takes place in steps over a wider range of temperature, with properties that are somewhere between the ordered molecular structure of a solid and the disorganized structure of a liquid. That longer
transition state is the liquid crystal state.

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