All Nan Ya LCD modules use either the high contrast supertwisted-nematic (STN) or the film-compensated FSTN display mode. These display modes provide much better contrast and greatly improved viewing angle characteristics over the older twisted-nematic (TN) display mode.

The viewing option encompasses (1) the background color of the STN-LCD, (2) the predominant viewing direction and (3) positive or negative contrast. Some factors to consider in specifying the viewing option include:

• The high contrast of STN-LCDs is due to the highly twisted structure of the liquid crystal molecules. However, this also results in a background coloration and display appearance which is different from the familiar black-on-gray TN-LCDs used in watches and calculators.
  
  
• STN-LCD display modes are defined by their background coloration:
  
  
  • Yellow mode STN-LCDs exhibit dark blue pixels on a yellow-green background. This mode provides the highest contrast for reflective and transflective LCDs.
    
    
  • Gray mode STN-LCDs exhibit medium blue pixels on a blue-gray background. This mode is often preferred over yellow mode STN because it provides a more neutral appearance.
    
    
  • Blue mode STN-LCDs exhibit clear pixels on a dark blue background. This mode is only used with transmissive LCDs in conjunction with an LED or CCFT backlight.
  
  
• FSTN-LCDs use optical retardation layers to provide a black-and-white display appearance with even higher contrast than standard STN-LCDs. Excellent contrast is achieved when used in conjunction with a CCFT backlight.
  
  
• Positive contrast (dark characters on a light background) and negative contrast (light characters on a dark background) LCDs are achieved by changing the orientation of the polarizers on the front and rear of the LCD panel. Negative contrast is only suitable for transmissive polarizer LCDs in conjunction with an LED or CCFT backlight.
  
  
• Unlike TN-LCDs, STN- and FSTN-LCDs provide excellent readability from all viewing directions. However, the LCD panel processing conditions dictate whether optimum readability is achieved when viewed from either below (6 o'clock viewing) or above (12 o'clock viewing) the centerline of the display.
  
  While 6 o'clock and 12 o'clock viewing directions are available options for all polarizer types, generally the best contrast and readability are achieved when 6 o'clock viewing is specified for reflective and transflective LCDs and 12 o'clock viewing is specified for transmissive LCDs.