As a consequence it is aligned with the second polarizer, passes through, reflects, and propagates out unattenuated. The entire display appears light gray as a result of polarizer and reflector tints. Application of a voltage across the LC causes the directors to rotate so they are parallel to the applied field. At a sufficiently high voltage, alignment is nearly parallel as shown in Fig. The 90-degree director twist is eliminated, for all practical purposes, and light propagating through the LC is absorbed by the second polarizer.
Dark digits appear in the active areas.
Director tilt increases with increasing voltage, and as a consequence, contrast develops first at lower voltages at shallow viewing angles. Multiplexed displays operate with voltage applied at all times. These two factors define the rms off voltage, as shown in Fig. 6. Good viewing also dictates that brightness be 50 percent or less for selected elements over the same 40-degree angle, and this voltage is also shown in Fig. Proper selection of the LC material, care in LC surface alignment, and care in maintaining proper cell spacing all serve to maximize viewing angle and contrast for a given application.