The LCDs put in projection systems are usually small reflective or transmissive panels lit up by a powerful arc lamp source. A series of lenses magnifies the reflected or transmitted image and then displays it onto the screen. With front-projection systems the LCD is located on the same area of the screen as the viewer, while in rear-projection systems the screen is illuminated from behind. Projectors of greater cost and capability may be found with three distinct LCD panels, reflecting separate red, green, and blue images that combine to make a coloured display on the screen.

The growing requirement for pictographic displays has had a growth in emphasis on the switching speed of liquid crystals. This has necessitated the creation of objects build with smectic liquid crystals, certain ones of which give a speedier electro-optical response than nematic liquid crystals. The surface-stabilized ferroelectric liquid crystal (SSFLC) display is at this time the most developed smectic device. Within it the liquid crystal molecules are arranged in layers that are perpendicular to the substrate planes, which are separated by one or two micrometres, and throughout the layers the molecules are tilted, as displayed in the figure. The host liquid crystal contains optically active molecules, and a subtle turn up of the optical activity and the shape of the molecules is the appearance of a permanent charge separation, or ferroelectric dipole, comparable to the ferromagnetic dipole of a magnet. The direction of this dipole is perpendicular to the tilt direction of the molecules and in the plane of the layers. Therefore, there exists a permanent charge separation throughout the liquid crystal layer in the SSFLC, and its sign is directly partnered to the tilt direction of the molecules. An applied voltage of the right sign can reverse the direction of this dipole in tens of microseconds and in so doing reverse the tilt direction of the molecules. The consequential change in optical properties can cause a change from light to dark when one or more polarizers are employed.

SSFLC devices have been produced for large passive-matrix presentations, but their high cost and complex nature has stopped them from enjoying any great movement on the market. Small transmissive and reflective active-matrix SSFLC displays, however, have some promise for use as aspects in projection systems or as viewfinders in digital cameras. Their immediate response allows them to be used in time-sequential colour systems, in which expensive colour filters are taken out for a coloured backlight that flashes red, green, and blue in rapid pulsing (around 100 cycles in a second). For example, the liquid crystal could be switched to a transmissive state in the red and green periods and then to a nontransmissive state during the blue period, with the result that the eye sees an average of red and green light, or the colour yellow.

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