Liquid crystal is an organic compound with regular molecular arrangement between solid and liquid. The most commonly used type of liquid crystal is nematic liquid crystal, and its molecular shape is slender rod, and its length and width are about 1 nm ~ 10 nm. Under the action of different current and electric field, liquid crystal molecules will rotate 90 degrees regularly, resulting in the difference of light transmittance, thus resulting in the difference of light and dark when the power supply is on/off. Each liquid crystal is controlled according to this principle.
1963, Willie Ames of RCA Company discovered that the light transmission mode of liquid crystal would change when it was electrically stimulated. Five years later, Haylumayia Group of the same company used this feature to invent a display device. This is the beginning of liquid crystal display. At the beginning, liquid crystal was very unstable as the material of display screen. Therefore, as a commercial use, there are still problems. However, in 1973, Professor Gray (University of Hal, UK) discovered a stable liquid crystal material (biphenyl system). 1976, Sharp applied it to the display screen of calculator (EL-8025) for the first time in the world, and this material has now become the basis of LCD materials.
Crystal liquid crystal-liquid crystal as early as 1850, Prussian doctor Rudolf? Virchow and others found that the extract of nerve fibers contained an unusual substance. 1877, German physicist Otto? Otto lehmann observed the liquid crystal phenomenon for the first time with a polarizing microscope, but he didn't know the reason of this phenomenon. Frederick, a plant physiologist at the German University in Prague, Austria? Friedrich Reinitzer studied the role of cholesterol in plants by heating cholesteryl benzoate, and observed the abnormal behavior of cholesteryl benzoate during the thermal melting process on March 1883+04. It melts at 145.5℃, producing a glossy turbid substance. When the temperature rises to 178.5℃, the luster disappears and the liquid is transparent. The clarified liquid cooled slightly, became turbid again, and instantly became blue, and the color was blue-purple just before crystallization began. After repeatedly confirming his findings, Lenin sought advice from the German physicist Lehman. At that time, Lehman built a microscope with heating function to discuss the cooling and crystallization process of liquid crystal, and later it was equipped with a polarizer, which was the most in-depth instrument for studying Lenezer compounds. Since then, Lehman's energy has been completely focused on such substances. At first, he called it soft crystal, and then renamed it crystalline liquid. Finally, he is convinced that polarized light is unique to crystals, and Fleeson de Cristal's name is correct. The name is only one step away from the liquid crystal (smooth ge crystal). Lenin Ze and Lehman were later called the fathers of liquid crystal. Oxyazo ether synthesized by L. gattermann and A Ristschke was also identified as liquid crystal by Lehman. However, in the 20th century, the famous scientist G. tammann and others thought that Lehman's observation was only a phenomenon that tiny crystals were suspended in liquid to form colloid. W. Nernst thinks that liquid crystal is only a mixture of tautomers of compounds. However, the efforts of chemist D. Vorlander enabled him to predict which compounds are most likely to show liquid crystal characteristics through aggregation experience, and then synthesize these compounds, so the theory was proved.
Liquid crystal is a polymer material. Because of its special physical, chemical and optical characteristics, it has been widely used in thin and light display technology since the mid-20th century. The familiar states of matter (also known as phases) are gas, liquid and solid, while the unfamiliar ones are plasma and liquid crystal (LC). Liquid crystal phase can only be produced by molecular combination with special shape. They can flow and have crystalline optical properties. The definition of liquid crystal has now been relaxed to include substances that can be liquid crystal phase in a certain temperature range and can crystallize normally at a lower temperature. The components of liquid crystal are organic compounds, that is, compounds centered on carbon. At the same time, liquid crystals with two substances are combined by intermolecular forces. Their special optical properties and sensitivity to electromagnetic fields have great practical value. 1888, an Austrian scientist named Leinitzel synthesized a strange organic compound with two melting points. When its solid crystal is heated to 145℃, it melts into a liquid, which is only turbid, while all pure substances are transparent when melted. If heated to 175℃, it seems to melt again and become a clear and transparent liquid. Later, German physicist Li Man called this turbid liquid "intermediate zone" crystal. It looks like a mule that is neither like a horse nor a donkey, so some people call it a mule in the organic world. Since it was discovered, people don't know its purpose. It was not until 1968 that people used it as a material for the electronic industry. The most common use of liquid crystal display materials is the display board of electronic watches and calculators. Why do they show numbers? It turns out that this kind of liquid crystal photoelectric display material uses the electro-optical effect of liquid crystal [1] to convert electrical signals into visual signals such as characters and images. Under normal circumstances, the molecular arrangement of liquid crystals is very orderly and appears clear and transparent. Once the DC electric field is applied, the molecular arrangement is disrupted, and some liquid crystals become opaque and dark in color, so that numbers and images can be displayed.