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LCD - What Does It Mean?

The basics about LCD technology displays

The production of images on a laptop screen is governed by the same colour perception notions utilised by television. Namely, that any picture viewed is composed of many red, green and blue dots. However, whilst the individual dots on a television screen represent a phosphor, on a laptop screen they represent a tiny device, more appropriately termed, “a cell.” or more often a "pixel".

LCD displays in detail

The matrix

A laptop screen is composed of a matrix of many tiny pixels or cells. The white light which passes through the screen flows through a red, green or blue filter at the end of each cell-thus the cell adopts the corresponding colour. Three red, green and blue cells taken together form a pixel , the colour of which is determined by the brightness of the three cells which compose it. Each pixel or cell contains liquid crystals, hence the terminology LCD or Liquid Crystal Display. Note that LCD has nothing to do with the Inverter or backlight of the display.

LCD, (liquid crystal display.)

The liquid crystals found in a laptop screen have molecular structures which adhere to the requirement of both a liquid and a solid. In fact, the slimy, liquid residue found at the bottom of a soap dish is a genuine example of such crystals and is not entirely dissimilar from the substance found in your laptop screen. 
However, you may wonder how a substance can have both liquid and solid molecular properties. For, the molecules in liquids fairly widely spaced in order to afford them their viscose characteristics, whilst those in solids are rigidly and compactly grouped.
This is indeed true. However, liquid crystals differ from ordinary liquids in terms of the shapes of the molecules which compose them. Whilst molecules in ordinary liquids behave in a disorderly manner, the molecules in liquid crystals are much longer and thinner. Thus, whilst their positioning is random their orientations can be aligned in unison to form a regular pattern. In this respect then, though they are liquids they can assume something of the ordered structure familiar in solids. 

The layers of a LCD screen 

In a laptop screen the liquid crystal substance is sandwiched between two plates of glass. One plate has horizontal grooves, the other vertical. The molecules present in the liquid crustal align themselves with these grooves-Thus a horizontal layer of molecules and a vertical layer is formed at both extremes of the sandwich. The intermediate molecules attempt to align themselves with the position of neighboring ones, thus a gradual spiral is formed reflecting the gradation from horizontal to vertical. This is termed a “twisted cell” of liquid crystal.

The light which passes through these twisted molecules is what lights up the laptop screen pixels.

Each cell consists of two Polaroid filters with a twisted liquid crystal cell between them, an adjustable electrical field and, as stated before, a green, blue or red filter. In order to vary the colours presented on a laptop screen, the computer can alter the strength of the electric field acting upon the molecules-the greater the strength the more the twisted molecular structures tilt. This affects the brightness of each cell and thus alters the colour of the pixel.

And, of course, as in the original television example we used, these differently coloured pixels combine to produce pictures of unbounded clarity, detail and precision.

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