The LCDs put for projection systems are generally small reflective or transmissive panels lit up by a bright arc lamp source. A number of lenses enlarges the reflected or transmitted image then casts it on a screen. In front-projection systems the LCD is situated on the side of the screen as the viewer, although in rear-projection systems the screen is lit up from behind. Projectors of greater expense and capability can use three separate LCD panels, forming separate red, green, and blue images that combine to reflect a coloured picture on the screen.

The increase in desire for visual displays has placed a growth in emphasis on the switching speed of liquid crystals. This has necessitated the development of devices employing smectic liquid crystals, some of which possess a better electro-optical response than nematic liquid crystals. The surface-stabilized ferroelectric liquid crystal (SSFLC) display is currently the most progressive smectic device. In it the liquid crystal molecules are cast in layers perpendicular to the substrate planes, which are distanced by one or two micrometres, and in the layers the molecules are on a slant, as displayed in the figure. The host liquid crystal contains optically active molecules, and a subtle result of the optical activity and the tilt of the molecules is the presence of a permanent charge separation, or ferroelectric dipole, analogous 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 has to be a permanent charge separation throughout the liquid crystal layer in the SSFLC, and its sign is directly attracted 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 in so doing reverse the tilt direction of the molecules. The respective change in optical properties can create a change from light to dark in the case that one or more polarizers are employed.

SSFLC devices have been publicized for bigger passive-matrix displays, but their high cost and complexity has prevented them from making any great movement on the market. Small transmissive and reflective active-matrix SSFLC displays, however, display some possibility for use as elements in projection systems or as viewfinders in digital cameras. Their immediate reacting allows them to be utilised in time-sequential colour systems, in which costly colour filters are emulated with a coloured backlight that flashes red, green, and blue in quick pulsing (around 100 cycles every second). For example, the liquid crystal might be switched to a transmissive state for the red and green periods but then to a nontransmissive state for the blue period, having the result that the eye sees an average of red and green light, or the colour yellow.

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