Other applications which index matching films are less appropriate are unsupervised applications such as ATM s or Kiosks since these films fingerprint very badly. Non polarized light is reflected back into the backlight assembly. In effect it sacrifices off angle brightness for direct view. It does absorb some light which so certain applications might be better off without this film. The diffuser spreads light evenly so bulbs are not visible in a direct backlight system.
Diffusers improve the light uniformity of a display.
Polyester films are highly reflective and diffuse and are ideal for reflector assemblies. Getting the best performance for a specific application and from a specific LCD is as much an art learned through experience as it is a science. Since a sunlight viewable display will be exposed to the elements of nature, your system considerations should be taken into account by your supplier of the display. Early involvement in the system design cycle by the display supplier is crucial to providing the most reliable and best performing system. The most important consideration relating to weather is LCD temperature absorption from direct sunlight.