Super twisted nematic is a higher information content liquid crystal cell structure that uses adjustable interference of two optical modes to achieve a large number of multiplexed lines, higher contrast and higher level of gray scale. This results in a birefringence effect. The STN LCD liquid crystal twist is generally between 240 and 270 degrees.
STN is capable of multiplex ratio up to 400:1, or 400 lines of text simultaneously, which makes STN suitable for higher content character displays and graphic applications. There are 3 common types of STN LCD displays.
Green Mode STN–Green mode is the most common STN type. It has a green background with a darker pixel.
Silver Mode STN–Silver mode uses a polarizer configuration that eliminates the green color of the background but at the expense of a lighter, more blue/purple pixel appearance.
Blue Mode STN–Blue mode is typically used in a negative (light pixel on a darker background) mode application with a white pixel on a blue background.