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How Projection Television Works


Projection TV Configurations
A transmissive, front-projection display system
A transmissive, front-projection display system
Photo courtesy Philips Research

Projection TVs are available in two main configurations -- front projection and rear projection.

A reflective, rear-projection display system
A reflective, rear-projection display system
Photo courtesy Philips Research

A front-projection system uses a projector and a separate screen, and it projects images onto the front of that screen. This setup looks most like what you'd find in a movie theater -- the projection unit is completely separate from the screen. The projector can be placed on a table or mounted to the ceiling. The picture looks best when displayed on a high-quality screen, but a specially painted, flat wall will work as well.

Rear-projection systems look more like traditional televisions. They display images on the back of a screen rather than the front, and the projector is completely contained within the television itself. You can also set up a rear-projection system with a projector and a special screen, but the term is most often used to describe self-contained TV sets.

Both configurations use tiny devices capable of making very detailed pictures. These devices can be reflective, meaning that light picks up the picture by bouncing off the device. Or, they can be transmissive, meaning that light picks up the picture by traveling through the device. Once the light picks up the picture, a lens magnifies the picture and projects it onto the screen.

Next, we'll take a look at the major types of television technologies and how they compare to one another.


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