DSTN LCD monitors

A normal passive matrix LCD comprises a number of layers. The first is a sheet of glass coated with metal oxide. The material used is highly transparent material so as not to interfere with the quality of the image’s integrity. This operates as a grid of row and column electrodes which passes the current needed to activate the screen elements. On top of this, a polymer is applied that has a series of parallel grooves running across it to align the liquid crystal molecules in the appropriate direction, and to provide a base on which the molecules are attached. This is known as the alignment layer and is repeated on another glass plate that also carries a number of spacer beads, which maintain a uniform distance between the two sheets of glass when they’re placed together. The edges are then sealed with an epoxy, but with a gap left in one corner. This allows liquid-crystal material to be injected between the sheets (in a vacuum) before the plates are sealed completely. In early models, this process was prone to faults, resulting in stuck or lost pixels where the liquid crystal material had failed to reach all parts of the screen. Next, polarising layers are applied to the outer-most surfaces of each glass sheet to match the orientation of the alignment layers. With DSTN, or dual scan screens, the orientation of alignment layers varies between 90 degrees and 270 degrees, depending on the total rotation of the liquid crystals between them. A backlight is added, typically in the form of cold-cathode fluorescent tubes mounted along the top and bottom edges...

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