About LCD Projectors
LCD projectors are the modern versions of slide and overhead projectors, and can display images such as video and computer data on a flat surface such as a screen. Many people refer to all types of computer projectors as LCD projectors, but this is a misconception, as there are many different types of projectors in the market, and a projector can technically only be called an LCD projector if it uses liquid crystal display technology.
History
In 1968, Gene Dolgoff, an inventor based in New York, wanted to build a projector with a brighter display than what the 3-CRT projectors available at that time had to offer. In 1984, he finally reached his goal using clear liquid crystal display technology. In 1988, he started a company called Projectavision, Inc., and the technology was later licensed to Panasonic and Samsung (see Resources below).
Development
Early LCD technology didn't come with a light source of its own, and so had to be combined with standard overhead projectors--the LCD screen basically sat on top of the space designed for transparencies in a regular overhear projector. Since home computers were not yet widely used, this use gave early LCD projectors only a limited market, but once personal computers began utilizing LCD technology, LCD projectors became very popular and created a huge market for LCD projectors. LCD projectors are also use in some rear-projection TVs (see Resources below).
How It Works
LCD projectors project a light beam from a metal halide lamp that passes through a special kind of prism that contains liquid crystals to help control and direct the intense light beam supplied by the metal halide lamp. The prism splits the light onto three panels made out of poly silicone. The first panel receives all the red-colored components of the image, the second gets all the green components and the third one gets all the blue components. When a polarized light is passed through these panels, individual pixels open up to allow the light to go through, or else they close down to block it--like the pupils in our eyes, which contract or expand to block light or let more in. This action of rapidly opening and closing pixels is what actually produces the images seen in LCD projectors (see Resources below).
The Future of LCD Projectors
With the introduction of more advanced projection technologies like DLP (Digital Light Processing), which offers better image contrast, the popularity of LCD projectors began to wane. LCD technology saw a small resurgence in popularity around 2005 with the introduction of a dynamic iris that could match the greater contrast offered by DLP technology. However, there are several other competing technologies that are poised to challenge LCD's popularity, such as plasma and LCoS, and it remains to be seen if LCD technology can keep up with these challengers.
Build Your Own
LCD home projectors can be built by hobbyists from a few basic parts that include a regular overhead projector, a cooling fan, an LCD panel (removed from an old or unwanted computer screen), a high CRI HID lamp and a fresnel lens (see Resources below).
Tags: Resources below, About Projectors, crystal display, crystal display technology, display technology
