Business Podcasting Blog

The LCDs put for projection systems are typically small reflective or transmissive panels set off by a bright arc lamp source. A series of lenses enlarges the reflected or transmitted image then sends it on a screen. In front-projection systems the LCD is situated on the same area of the screen as the viewer, however in rear-projection systems the screen is illuminated from behind. Projectors of greater cost and capacity may be found with three distinct LCD panels, creating separate red, green, and blue images that combine to create a coloured picture on the screen.

The increase in need for film displays has placed a growing emphasis on the switching speed of liquid crystals. This has required the creation of items utilizing smectic liquid crystals, particular kinds of which give a better electro-optical response than nematic liquid crystals. The surface-stabilized ferroelectric liquid crystal (SSFLC) display is currently the most developed smectic device. Inside it the liquid crystal molecules are set out in perpendicular layers to the substrate planes, which are differentiated by one or two micrometres, and in the layers the molecules are tilted, as illustrated in the figure. The host liquid crystal contains optically active molecules, and a slight turn up of the optical activity and the shape 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. So, 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 right sign can reverse the direction of this dipole in tens of microseconds and by doing so reverse the tilt direction of the molecules. The resultant change in optical properties can make a change from light to dark if or when one or more polarizers are used.

SSFLC devices have been marketed for large passive-matrix presentations, but their cost and detail has stopped them from having any particular movement on the market. Small transmissive and reflective active-matrix SSFLC displays, however, show some promise for use as elements in projection systems or as viewfinders in digital cameras. Their immediate response allows them to be used in time-sequential colour systems, in which highly expensive colour filters are removed for a coloured backlight that flashes red, green, and blue in fast pulsing (approximately 100 cycles in a second). For example, the liquid crystal might be switched to a transmissive state for the red and green periods but to a nontransmissive state during the blue period, creating the upshot that the eye sees an average of red and green light, or the colour yellow.

For help with choosing and purchasing your data projector, contact projectors brisbane and projectors gold coast.