Figure 1: TN+Film displays align their liquid crystals perpendicular to the substrate, in the same way as standard TFTs do. A film on the upper surface increases the viewing angle.
From a technical point of view, the TN+Film solution is the simplest to implement. The flat panel manufacturers use the relatively old standard TFT (T wisted N ematic) technique that we previously described in Part1 . A special film (retardation or discotic film) is applied to the top surface of the panel which improves the horizontal viewing angle through the film from about 90 degrees to approximately 140 degrees. However, the poor contrast ratio and the slow response time remain unchanged. The TN+Film method isn't the best solution but it is definitely the most inexpensive as the manufacturing yield is relatively high (virtually identical to that of standard TN displays).