Liquid Crystal (Liquid Crystal) is a polymer material, because of its special physical, chemical, optical characteristics, the middle of the 20th century began to be widely used in thin and light display technology.
People are familiar with the material state (also known as phase) for the gas, liquid, solid, more unfamiliar is the plasma and liquid crystal (Liquid Crystal, referred to as LC). Liquid crystal phase to have a special shape of the combination of molecules will be generated, they can flow, but also has the optical properties of crystallization. The definition of liquid crystal, now to relax and include in a certain temperature range can be the liquid crystal phase, at a lower temperature for the normal crystallization of the material. The liquid crystal composition is an organic compound, that is, carbon as the center of the composition of the compound. At the same time with two substances in the liquid crystal, is the combination of intermolecular forces, their special optical properties, but also sensitive to electromagnetic fields, very practical value.
In 1888, Australia called Lennitzer's scientist, synthesizing a strange organic compound, which had two melting points. When it is heated to 145 ° C solid crystal, it is melted into a liquid, but it is turbid, and all pure substances are transparent when melted. If it continues to heat to 175 ° C, it seems to melt again and become a clear and transparent liquid. Later, the German physicist Lehman in the "middle zone" of the turbid liquid called crystal. It is like neither a horse nor a donkey's mule, so somebody calls it a mule for the organic world. Since the discovery of liquid crystal, people do not know what it uses, until 1968, people put it as the electronics industry on the material.
The most common use of liquid crystal display material is the display panel of the electronic watch and the calculator. Why is the number displayed? The original liquid photoelectric display material, the use of liquid crystal electro-optical effect of electrical signals into characters, images and other visible signals. Liquid crystal in the normal circumstances, the molecular arrangement is very orderly, it is clear and transparent, once coupled with the DC electric field, the molecular arrangement is disrupted, part of the liquid crystal becomes opaque, color deepened, which can display numbers and images.
The electro-optic effect of liquid crystal refers to its optical phenomena such as interference, scattering, diffraction, rotation, absorption and so on. Some organic compounds and macromolecules, in a certain temperature or concentration of the solution, both with the liquid flow, but also has the crystal anisotropy, which is the liquid crystal. Liquid crystal photoelectric effect by the temperature conditions of the liquid crystal is called thermotropic liquid crystal; soluble liquid crystal is controlled by the concentration conditions. Display with liquid crystal is generally low molecular thermotropic liquid crystal.
According to the characteristics of LCD will change color, people use it to indicate the temperature, alarm gas and so on. For example, the liquid crystal can change with the temperature, the color from red to green, blue. This can indicate the temperature in an experiment. Liquid crystal encounter hydrogen chloride, hydrocyanic acid and other toxic gases, will change color. In the chemical plant, people put the liquid crystal chip hanging on the wall, once there is a trace of gas escape, LCD discoloration, to remind people to quickly check, trap.
Many types of liquid crystal, usually according to the liquid crystal molecules of the central bridge and ring characteristics of the classification. Has been synthesized more than 10,000 kinds of liquid crystal materials, which are commonly used in liquid crystal display materials are thousands, mainly biphenyl liquid crystal, phenyl cyclohexane liquid crystal and ester liquid crystal. Liquid crystal display material has obvious advantages: low driving voltage, low power consumption, high reliability, display information, color display, no flicker, no harm to the human body, the production process automation, low cost, can be made into a variety of specifications and Type of liquid crystal display, easy to carry and so on. Because of these advantages. Computer terminals made with liquid crystal materials and television can significantly reduce the volume and so on. Liquid crystal display technology on the display display product structure had a profound impact, and promote the development of microelectronics technology and optoelectronic information technology.