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The LCDs used for projection systems are usually small reflective or transmissive panels illuminated by a bright arc lamp source. A line of lenses enlarges the reflected or transmitted image and then displays it on a screen. With front-projection systems the LCD is located on the same area of the screen as the viewer, but in rear-projection systems the screen is lit from behind. Projectors of higher expense and capacity can be found with three separate LCD panels, casting separate red, green, and blue images that blend to reflect a coloured picture on the screen.

The growing need for pictographic displays has had a growth in emphasis on the switching speed of liquid crystals. This has required the development of devices build with smectic liquid crystals, particular kinds of which give a speedier electro-optical response than nematic liquid crystals. The surface-stabilized ferroelectric liquid crystal (SSFLC) display is at this point the most sophisticated smectic device. With it the liquid crystal molecules are set out in perpendicular layers to the substrate planes, which are separated by one or two micrometres, and throughout the layers the molecules are tilted, as demonstrated in the figure. The host liquid crystal holds optically active molecules, and a slight consequence of the optical activity and the tilt of the molecules is the presence of a permanent charge separation, or ferroelectric dipole, similar to the ferromagnetic dipole of a magnet. The direction of this dipole is perpendicular to the tilt direction of the molecules and within the plane of the layers. Hence, there is a permanent charge separation through the liquid crystal layer in the SSFLC, and its sign is directly paired to the tilt direction of the molecules. An applied voltage of the corresponding sign can reverse the direction of this dipole in tens of microseconds and therefore reverse the tilt direction of the molecules. The respective change in optical properties can effect a change from light to dark in the case that one or more polarizers are employed.

SSFLC devices have been marketed for big passive-matrix displays, but their high cost and intricacy has hindered them from making any great effect on the market. Small transmissive and reflective active-matrix SSFLC displays, however, have shown some possibility for use as parts in projection systems or as viewfinders in digital cameras. Their quick reaction allows them to be employed in time-sequential colour systems, in which highly expensive colour filters are emulated by a coloured backlight that flashes red, green, and blue in rapid speed (approximately 100 cycles a second). For example, the liquid crystal could be switched to a transmissive state during the red and green periods then to a nontransmissive state in the blue period, with the end result that the eye sees an average of red and green light, or the colour yellow.

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