Transmission displays

FIGURE 33.1 Schematic illustration of (a) a smart window or transmission display (b) a front-illumination display (c) an antidazzle mirror. (From Bohnke, 1992, with permission of Cambridge University Press.)... 

A numerical evaluation of the maximum number of lines that can be multiplexed with such a single-frequency scheme requires specification of the acceptable viewing angle, temperature dependence of the various parameters, and so on see Kahn and Birecki (1980). The present upper limit appears to be about 25 lines for a direct view, temperature-compensated TN LCD and 91 for a transmission display, but further progress in LC chemistry will increase this number in the future. 

A director patterned retarder can be used in a transflective LCD to boost the optical performance and to lower the power consumption. A transflective display is the combination between a reflective and a transmissive display. 

In using the above definitions of Voff and on we have chosen to consider two extreme cases of the angular variation of the optical transmission only. One case is that of a transmissive display where the viewing direction is restricted to normal incidence. 

Figure 9 shows the effect of the variation of Ac from zero to twenty while keeping at five. For transmissive displays, the dependence is weak. For reflective displays, it is stronger and a low value of Ae is to be preferred. 

Actually, much higher values can be obtained. For example, if Voff and Von transmissive display are chosen equal to the voltages at 1% and 15% transmission, respectively, can... 

Here the alignment layer is patterned so that in one subpixel, the LC is in the bend alignment, and it is a TN cell in the other subpixel. By adjusting the retardation of the bend cell, it can be seen that this display can function as a reflective display as well as a transmissive display at the same voltages. 

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