Why An LCD Projector Is Worth Looking At.
LCD panels have become fairly mature technology, so you can get LCD projectors pretty cheaply these days. Units supporting SVGA (800x600) resolutions can be purchased for well under $2000, manufactured by Sanyo, Viewsonic, and others.
The type of projector refers to the type of display technology used on the projector. LCD projectors are the standard, with polysilicon being of a higher quality than the standard LCD active matrix display. "Digital Light Processing (DLP)" and "Light Valves" are the newest forms of projector technology. DLPs are considered to have brighter images, as well as superior video quality, than LCD's. Light Valves, being very powerful and bright projectors, tend to be found on the largest models (and most expensive), such as those used in auditoriums and theaters.
Most multimedia projectors create their images by aiming bright light through small LCD panels containing a grid of thousands of "gates," each of which can be opened or closed to control the brightness and color of light at a given pixel on the screen. Since the panel grid blocks some of the light, this is an inherently inefficient process. However, DLP eliminated this inefficiency. Instead of LCD panels, DLP relies on small chips that contain arrays of tiny mirrors, which can be moved to control the brightness and color of light at a given pixel. This arrangement allows nearly all of the light output to make it to the screen.
ANSI lumens for
projectors currently range from 400 to 1,000 for ultra lights up to as
much as 10,000 for fixed machines. For on-the-road presentations, 500 to
1,000 ANSI lumens should be fine. Larger conference rooms will need
1,000 to 2,000 lumens, while fixed installation machines will need to
project between 2,500 and 10,000 lumens to handle auditoriums or other
large venues. The brightness of a projector can sometimes be
misrepresented, so be sure to check the brightness of the individual
model and not the published brightness of the model line.
An LCD can be moved
from room to room and requires no more set-up than a slide projector. At
the heart of the LCD are a number (usually three) of liquid crystal
panels. All are illuminated by a single high-wattage metal halide lamp.
A complex series of dichroic reflectors and filters split the spectrally
pure white light into rays of red, green and blue. Each of these beams
illuminates a liquid crystal panel. The images from the panels converge
at the focal point of a single lens. Focus and zoom are provided and on
many models are controlled via an IR handset.
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