Enormous televisions and home theaters used to be a real luxury. But in the last few years, many people have started to view large screens with great pictures as necessary for watching TV and movies at home. Although old-fashioned cathode ray tube (CRT) TVs can provide a great picture, they can't support the screen size that people look for today. Projection TVs can provide a much bigger picture than CRT sets can, and front- and rear-projection models can suit a range of rooms and budgets.

Shopping for a projection TV? Read projection TV reviews and compare prices on top models at Consumer Guide Products.

In this article, we'll discuss the differences between front- and rear-projection TVs. We'll also explain the differences between the various types of projection TV technology and what to look for when you go shopping.

A good way to understand how a projection TV works is to compare it to a standard TV. A conventional television uses a cathode ray tube (CRT) to create a picture.

A CRT fires a beam of electrons at a phosphor-coated screen. Every time an electron comes into contact with the screen, that point, called a pixel, glows. Color CRT televisions use three electron beams and separate phosphors for red, green and blue. When you watch, you're looking directly at the surface that the TV uses to create the picture. That's why traditional CRT sets are called direct-view displays.

CRTs are very reliable and have good picture quality. But they do have one big drawback -- since the screen is made of glass, size is limited. The largest CRT screens measure about 40 inches diagonally. A CRT TV with a screen that size is deep, heavy and unwieldy.

That's the main reason for projection TVs. Even though some models can't rival the quality of a direct-view CRT set, they can be much bigger. Instead of using a direct-view setup, a projection TV creates a small picture and then uses a beam of light to display that picture at a much larger size.

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

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

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.

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

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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