Contrast Ratio, Transmission Brightness, and Switching Speed

2 Contrast Ratio, Transmission, Brightness, and Switching Speed 

one has to make a compromise between contrast and operating voltage. The light is significantly elliptically polarized in normal White-Taylor mode LCDs, as p is kept moderately large (much more than A/Wg) in order to reduce the operating voltage and memory. 

The impact of host birefringence and the number of helical turns on the contrast ratio of the display is illustrated in Fig. 19. The fact that these curves are nearly straight 

Dichroic displays presently used in avionics have a reflective contrast ratio of 25 1 and a transmissive contrast of about 6 1 with a brightness of over 18% at a 45° viewing angle. These displays operate from -30° to +85 °C. The low-temperature operation is assisted by a heater. 

Scheffer and Nehring proposed a useful index/, for selecting a host material to give lower operating voltage by combining the linear relationship of versus An for a fixed contrast and the threshold voltage relationship with material parameters. 

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