The performance of an LCD monitor ultimately depends on how its liquid crystals are manipulated to channel light. We’ll examine the three most common technologies: Twisted Nematic (TN), In-plane Switching (IPS), and Vertical Alignment (VA).
Each of these three technologies creates a pixel using a cell of liquid-crystal molecules controlled by a thin-film transistor. Liquid crystals are used because they’re capable of effecting light as though they’re a solid, while exhibiting the malleability of a fluid. In a color LCD, each pixel is subdivided into three cells, or subpixels, which are colored red, green, and blue, respectively, by additional filters. These cells are arranged in a matrix of rows and columns sandwiched between two panes of glass, with a polarizing film on the exterior side of each pane.
A light source, such as a cold cathode fluorescent lamp or an LED grid, is placed behind the first glass panel. Light waves from the backlight follow the alignment of the liquid-crystal molecules, but they must pass through the two polarizing filters before reaching the surface of the display. Light waves must be oriented perfectly parallel to the first filter to pass, but since the second filter is oriented perpendicular to the first, no light will pass unless it’s reoriented first.
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