When looking at the differences between TN and STN, the difference lies in the angle in which it is twisted. TN is twisted at an angle of 90 degrees, while STN can have an angle between 90 and 270 degrees. This provides more contrast than twisted nematic (TN) displays. With the change of twisted angle and different angles of polarizer film, STN can display yellow-green, blue and gray modes. STN is superior to TN in more duty cycles and excellent opto-electro functions. STN also require less power and are less expensive to manufacture than TFT LCDs, another popular type of LCD. However, STN displays typically suffer from lower image quality and slower response time than TFT displays. STN displays are used in some inexpensive mobile phones and informational screens of some digital products.
FSTN has special retardation films added with the rear polarizer to make up for the interfering color of STN so that a true color can be seen. Different angles of the film can create more options, i.e. positive, white/gray background with black font; negative, black background with gray/white font.