Liquid Crystalline materials used in LCD display

Liquid Crystalline materials used in LCD display

A Liquid Crystal Display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystalline compounds. Liquid crystalline compounds do not emit any kind of light directly, but by using a backlight or reflector to produce images in color or monochrome1. LCDs are available to display arbitrary images (as in a general-purpose computer display) or fixed images with low information content, which can be displayed or hidden, such as preset words, digits, and seven-segment displays, as in a digital clock. They use the same basic technology, except that arbitrary images are made up of a large number of small pixels, while other displays have larger elements .

The display setup of LCD screen made by liquid crystalline materials.

Liquid crystal displays (LCDs) consist of liquid crystals that are activated by electric current. They are used most frequently to display one or more lines of alpha-numeric information in a variety of devices: fax machines, laptop computer screens, answering machine call counters, scientific instruments, portable compact disc players, clocks, and so forth. The most expensive and advanced type active matrix displays are even being used as screens for handheld color TVs. Eventually; they may be widely used for large screen, high-definition TVs6-8. Thermotropic LCs are mainly divided into three categories SmA, SmC, Nematic and Cholesteric phase in which nematic mesophase are mostly used in LCD display.

Various types of thermotropic liquid crystals.

Most LCDs today also use a source of light coming from the rear of the display (backlight), such as a fluorescent light, to make the liquid crystal appear darker against the screen when in its cloudy phase8. LCD makers also use sheets of polarizer material to enhance this effect9. The texture pattern of smectic phase is generally appeared in broken fan type and nematic phase appeared schlieren and threaded type texture pattern having good mobility. Currently, the room temperature liquid crystalline material 5 CB is mostly used in liquid crystalline display as compare to other liquid crystalline derivatives respectively.

POM texture image of smectic and nematic phase

References

  • Datta, Asit Kumar; Munshi, Soumika (2016-11-25). Information Photonics: Fundamentals, Technologies, and Applications., CRC Press., ISBN 9781482236422.
  • Kawamoto, Hiroshi (2002). "The History of Liquid-Crystal Displays" (PDF). Proceedings of the IEEE., 90., 460–500.
  • Gray, George W.; Kelly, Stephen M. (1999). "Liquid crystals for twisted nematic display devices". Journal of Materials Chemistry., 9 (9)., 2037–2050.
  • Williams, R., "Domains in liquid crystals". J. Phys. Chem., 1963, 39.,382–388.
  • Electro-optical color display device and projection apparatus; A.J.S.M. de Vaan, US patent US5029986., 9 July 1991.
  • Pixel-by-pixel local dimming for high dynamic range liquid crystal displays; H. Chen; R. Zhu; M.C. Li; S.L. Lee and S.T. Wu; Vol. 25, No. 3; 6 Feb 2017; Optics Express 1973
  • New Cholesteric Colour Filters for Reflective LCDs; C. Doornkamp; R. T. Wegh; J. Lub; SID Symposium Digest of Technical Papers., 2001, 32, 456–459.
  • , G. H.; Zanoni, L. A.; Barton, L. A. (1968). "Dynamic scattering: A new electrooptic effect in certain classes of nematic liquid crystals". Proc. IEEE. 56: 1162–1171
  • S.M.Yanic, Dilek Guzzeller, H.Ocak, F.Cakar, I.Erol and O.Cankurtaran., Mol.Cryst.Liq.Cryst., 607, 2015, 23-31.
  • K.Binnemans., Handbook on the Physics and Chemistry of Rare Earths., 43, 2013, 1-158.
  • V.Causian, G.Sailli., Green Solvents II, 2012, 79-118.


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