Emerging Display Technology
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03-03-2011, 11:43 AM
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Emerging Display Technology
Display technology plays a critical role in how information is conveyed. As a picture is
worth a thousand words, display technology simplifies information sharing. Since its commercialization in 1922 up until the late 20th century, Cathode Ray Tube technology (CRT) has dominated the display industry. However, new trends such as the desire for mobile electronics have increased demand for displays that rival and surpass CRTs in areas such as picture quality, size, and power consumption. One of the latest devices likely to replace CRTs is Liquid Crystal Displays (LCD) due to their lightweight, low operating power, and compact design. LCDs allowed devices such as digital watches, cell phones, laptops, and any small screened electronics to be possible. Although LCDs were initially created for handheld and portable devices, they have expanded into areas previously monopolized by CRTs such as computer monitors and televisions. Other contenders for leadership in display technology are Organic LEDs, DLP technology, Plasma Displays, Field Emission Displays, and Electronic Paper. Organic LEDs, being composed of light emitting polymers, can emit their own light to offer thin and power-saving displays. Using many microscopic mirrors, DLP technology can generate large bright project and implimentationions on screens with up to 35 trillion colours. Plasma Displays generate excellent quality images on very large screens. Field Emission Displays can produce high resolution images like CRTs without the bulky appearance. The makers of Electronic Paper are trying to replace print by developing displays with many paper-like properties. Demand for higher quality displays will drive technology evolution ; this evolution will require new approaches and innovative ideas in information presentation.
2.0 LIQUID CRYSTAL DISPLAY
Liquid crystals were discovered in 1888, but their potential application in display technology was not realized until 1968 when researchers from the RCA’s David Sarnoff Research Center developed the first liquid crystal display. Since then, LCDs have revolutionized the small screen and portable electronic market offering an alternative to CRTs and making devices like calculators, cell phones, PDAs, and laptops possible. As LCD designs advance, they will remain a popular part of home entertainment systems and continue to dominate handheld electronics.
2.1 Liquid Crystals
An Austrian botanist by the name of Friedrich Reinitzer was the first person to perform research on liquid crystals. In 1888 he conducted an experiment involving a material known as cholesterly benzoate. In his experiment Reinitzer observed changes in a solid sample of cholesterly benzoate as he increased the applied temperature. He noticed that as the temperature increased the solid sample became a hazy liquid and then changed into a transparent liquid. A physics professor named Otto Lehmann having learned of Reinitzer’s discovery conducted his own research confirming that the substance seem to have two distinct melting points; his research led him in 1889 to coin the term ‘liquid crystal’
Liquid crystals are substances that exhibit properties of both solids and liquids; they are an intermediate phase of matter. Liquid crystals can be classified into three different groups, nematic, smectic, and cholestric depending on the level of order in their molecular structure. Liquid crystals in the nematic group are most commonly used in LCD production because of their physical properties and wide temperature range. In the nematic phase, liquid crystal molecules are oriented on average along a particular direction. By applying an electric or magnetic field, the orientation of the molecules can be manipulated in a predictable manner; this mechanism provides the basis for LCDs.
There are a variety of different liquid crystal compounds, which exhibit nematic phases but not all are suitable for use in displays. The phase of matter a substance exhibits is greatly dependant on its temperature. Although many different liquid crystals exhibit nematic phases, they do not do so at room temperature. The first room temperature nematic liquid crystal was observed in 1969 in the compound 4-methoxybenzyliden-4’-butylanilin (MBBA for short). MBBA had major drawbacks including a short stable temperature range that was greatly affected by impurities; these drawbacks prevented MBBA from being used in commercial LCDs and prompted further research to be conducted to find a more stable liquid crystal.