Projection displays

The pioneering work of Natta and co-workers introduced the concept of tacticity, i.e. the orderliness of the succession of configurational repeating units in the main chain of a polymer. For example, in polypropene (polypropylene), possible steric arrangements are (shown in Fischer projections displayed horizontally) ... 

Besides the direct electrical induction of electro-optical effects in liquid crystals, their activation by illumination of photoconductors could be of great technical interest. This method might well permit the electro-optical properties of nematic liquid crystals to be used on a larger scale, because photoconductor activation may eventually be applied to light amplification, optical data processing, and projection display systems, or used for recording phase-type holograms. 

The groups found in this project display variation in their chemical composition. Because sources were not analyzed in this study, the variation in the sources cannot be quantified. However, the variation in die groups implies different procurement practices or variation within the procurement site. Depending on the source and the geochemistry of the region, differing elements... 

Miyama T, Kundu S, Shiraki H, Sakai Y, Shiraishi Y, Toshima N, Kobayashi S (2004) Proc SPIE - Liquid Crystal Materials, Devices, and Applications X and Projection Displays X 5289 143... 

As stated above, room mounted multi-screen projection displays are nowa-... 

Colour separation and recombination in projection displays is made with the Color Cube . The device is optimized in uniformity, reliability and repeatability for high resolution projection systems requiring dichroic prisms [91]. 

We show here how to determine the number of rows N that can be multiplexed, i.e., the minimum multiplexing duty factor 1/N, from either measurements on actual displays or by computation of the static optical properties of TN-LCDs. We show that the figure of merit M can be decomposed into multiplicative factors Mvf Mq and specifying dependence on voltage, angle and temperature respectively. It is shown that these multiplicative factors permit customizing computations of N to match specific user requirements such as direct viewed or projection displays and temperature compensated or uncompensated drive voltage. 

Higher values of N for projection displays could be obtained by tilting the cell and adjusting the polarizers to get higher My such as discussed by Goscianski (M. Goscianski, J. Appl. Phys. 48 1426 (1977)). For example, if My 0.95, then N=381. 

A. G. Dewey, et al., A 2000 Character Thermally-Addressed Liquid Crystal Projection Display, Proc. 1977 SID Inti. Symp., pp. 108-109. 

A. G. Dewey, J. T. Jacobs and B. G. Huth, Laser-Addressed Liquid Crystal Projection Displays, Proc. SID, Vol. 19/1,... 

The smectic A is an untilted phase in which the mass density wave is parallel to the director. The cost in free energy of buckling the layers into saddle-shaped deformations is low, with the result that it is relatively easy to construct devices that show bistability between a scattering focal conic director configuration in which the layers are buckled and a clear homeotropic configuration in which the director is perpendicular to the cell walls and the layers parallel to the walls. Transitions between these two textures have been exploited in laser-written projection displays and in both thermo-optic and electrooptic matrix displays. The various mechanisms employed are summarized in Fig. 12. 

Both CdS and a-Si have been successfully used as the photocondoctor 45°-twisted nematic layers and, on an experimental basis, ferroelectric layers have been used for the liquid crystal. CCD structures and silicon vidicon microdiode arrays have been used in place of the photocon-ductive layer. The device is useful both when the write beam is coherent (for example, a scanned laser) and when it is incoherent (for example, a CRT). In the latter case, the SLM can be used as an incoherent-to-coherent converter. The CRT-written device has also found application as a projection display. There exists a very large potential market for optically addressed SLMs in a variety of optical processing applications and for projection displays. 

The temperature effect is particularly important for projection displays [16] Due to the thermal effect of the lamp, the temperature of the display panel could reach 50°C. It is important to know the LC properties at the anticipated operating temperature beforehand. The thermal non-linearity of LC refractive indices is also very important for some new photonic applications, such as LC photonic bandgap fibers [17,18] and thermal solitons [19,20]... 

Similarly, the reflective LCDs can be subdivided into direct-view and projection displays. In principle, a direct-view reflective LCD does not require a backlight so that it is light in weight and its power consumption is low. A major drawback is poor readability under weak ambient light. Thus, a reflective LCD is more suitable for projection TVs employing liquid-crystal-on-silicon (LCoS) microdisplay panels. In an LCoS, the reflector employed is an aluminum metallic mirror. The viewing angle is less critical in projection displays than in direct-view displays. 

E. H. Stupp and M. Brennesholtz, Projection Displays (Wiley, New York, 1998). 

Several MTN modes with twist angle varying from 45° to 90° have been used for direct-view and projection displays, depending on the desired contrast ratio and optical efficiency. In transflective LCDs, the 75° and 90° MTN cells are frequentiy used. Therefore, we only discuss these two modes here. 

For direct-view reflective displays, the outmost surface reflection (usually it is a plastic protective film without anti-reflection coating) limits the device contrast ratio. Thus, the -100 1 contrast ratio of the 75° MTN is still adequate. However, in projection displays the contrast ratio needs to exceed 1000 1. The 90° MTN and the VA cells are the better choices. 

Let us design a normally black reflective LCD using a 45° twisted nematic cell for projection displays. We want the display to be independent of beta angle ( ) the angle between the top LC rubbing direction and the incoming polarization axis. What is the required d n value at 2 = 550 nm ... 

Figure 11.33 Schematic diagram of the projection display from the scattering liquid crystal/polymer composite.

A. Tomita, P. Jones, Projection displays using nematic dispersions, SLD Lntl Symp. Digest Tech. Papers, 23, 579 (1992). 

Y. Ooi, M. Sekine, S. Niiyama, et al., LCPC project display system for HDTV, Proc. Japan Display, 92, 113-116 (1992). 

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