double super twisted nematic (display) (DSTN)
Double Super Twisted Nematic (DSTN) is a display technology for monochromatic displays, which is characterized by a higher contrast compared to TN technology and STN technology.
The DSTN cell differs from the TN cell in that it has an additional active liquid crystal cell that compensates for the unwanted color effect of STN technology. In the DSTN cell, the incoming light is linearly polarized in a polarizer. This light can pass through the downstream active liquid crystal cell when the LCD cell is activated; when the LCD cell is inactive, it circularly polarizes the light. The light passes through another passive liquid crystal lens in which the linearly polarized light (active DSTN cell) is circularly polarized and the circularly polarized (inactive DSTN cell) is linearly polarized. The circularly polarized light can pass through the last polarizer and is bright for the observer, the linearly polarized is blocked by the last polarizer, the DSTN cell remains dark.
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DSTN technology is quite expensive to manufacture and has been superseded by Film Super Twisted Nematic( FSTN) and Triple Super Twisted Nematic( TSTN). DSTN technology was used in notebooks, works passively and was slower and lower in contrast than the active TFT displays. This is due to the fact that the liquid crystals are only aligned for a brief application of an electric field, but then lose their alignment again. That's why inertliquid crystals are used, which cause a trailing effect with moving images.