Liquid Crystal Displays and LCD TVs.



Posted: Wednesday, December 03, 2008

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LCD stands for Liquid Crystal Display, referring to the technology behind the increasingly popular flat  panel monitors. An LCD monitor or  TV is distinguishable from a traditional CRT monitor in its size. An LCD TV is  sleek, thin, and dynamic as opposed to the heavy, bulky and box-like cube of a  CRT. The reason  is that there are only a couple of pieces of glass that are holding liquid  crystals inside to create the picture.

LCD displays were initially invented to be used on  laptop computers before the technology improved enough to make the jump to  desktop monitors, and then again to televisions. Overall, an LCD monitor consists of five layers: a backlight,  a sheet of polarized glass, a ‘visor' of coloured pixels, a layer of liquid  crystal solution, and a second polarized sheet of glass. By manipulating the  orientations of crystals through precise electrical charges of varying degrees  and voltages, the crystals act like tiny shutters, opening or closing in  response to the stimulus, thereby allowing degrees of light that have passed  through specific coloured pixels to illuminate the screen, creating the picture  that you see.

So what is Liquid  Crystal…besides an obvious contradiction in terms?
We know that there are three common states  of matter: solid, liquid or gaseous. With solids, the molecules always  maintain their orientation and stay in the same arrangement with respect to one  another.

The molecules in liquids are completely the opposite: They can change their orientation and move  anywhere within the liquid. But there are some substances that can exist in an  in between state, that can be influenced by temperature, similar to that of a  liquid and at the same time resembling a solid. This means that liquid crystals  are neither a solid nor a liquid. That's how they ended up with their seemingly  contradictory name.

So, do liquid crystals act like solids  or liquids or something else?
It turns out that liquid crystals are  closer to a liquid state than a solid. It takes a fair amount of heat to change  a suitable substance from a solid into a liquid crystal, and it only takes a  little more heat to turn that same liquid crystal into a real liquid.

Along with the in between state of the  liquid crystal, there are some fluxuations in the performance of an LCD TV. As  opposed to CRTs, LCDs cannot form multiple resolution images. LCD's can only  produce clear images in their native resolution or a small fraction of it. The  contrast ratio for LCD images is less than its CRT and plasma counterparts.

Due to their longer response time, LCDs may  show ghosting and mixing when images change rapidly. The viewing angle of an  LCD is narrower than a CRT or plasma display, thereby restricting the number of  people who can conveniently view the image on the screen at one time. Image  persistence is a common phenomenon with LCDs.

This is something comparable to screen burn-in  on CRTs. As liquid crystal structure evolves, so will these difficulties with  the picture qualities.

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