NOTE: All photos in the following article were taken by your Guide.
The days of projection TVs that took up half the living room with their, bulky cabinets, only viewable in total darkness, with everyone crowded around the center of the screen, and high prices are gone. Today's projection TVs are brighter, slimmer, viewable from the same angles as other TVs and with prices for entry-level sets in the $1,000 and less price range, they have become more affordable than ever.
Projection TV Technology
Up until recently, big screen projection TVs basically came in two flavors: CRT-based and LCD-based. The CRT or LCD generated image is generated inside a "box", reflected off of a mirror and projected onto a screen. Another type of projection experience consists of a CRT-based or LCD-based projector that is mounted on a ceiling or placed on a table and projected onto a wall-mounted screen. These systems allow for larger images, but can suffer from dimness in lower-end systems. Generally speaking the "box" system is less expensive for the consumer, while the separate projector-screen systems are reserved for higher-end home theater system in which an entire room is devoted for viewing films or TV programs.
Plasma and LCD flat panel TVs have entered the market as an alternative to both projection and tube TV, and are making their way into more homes. The main attraction of Plasma and LCD flat panel sets is the fact they are flat enough to be wall mounted, thus eliminating the need for that "box" or separate projector.
Plasma and LCD flat panel TVs are an improvement. They are bright, have acceptable contrast levels, practical as both TV or computer monitors, and can be hung on the wall. Two drawbacks: A lot glass and, although come in large screen sizes, they get a lot more expensive as the screen size goes up.
Enter Digital Light Processing
A technology is commonly available that changes the nature of projection TV: DLP (Digital Light Processing), invented and developed by Texas Instruments.
The key to DLP is the DMD (Digital Micro-mirror Device). In essence, every pixel on a DLP chip is a reflective mirror, which amplifies the light reflected off the chip. Since the light reflected by each pixel is amplified, there is no limit to the size of the screen that can be manufactured. Brightness and contrast is even across the entire surface of the screen.
There are two ways that DLP images are projected.
One way is to have a separate DLP chip for each primary color. Light from a single source is passed through a prism, which creates separate red, green, and blue light sources, and then reflected on each of the chips designated for each primary color.
The second, more economical, way to project images using DLP technology is to use a single DLP chip. This method utilizies a single light source that is used to pass white light through a segmented, spinning color wheel, which is then reflected off the DLP chip to the screen.
The advantage of DLP is two-fold: (1) It produces bright, high-contrast images, viewable from a wide angle, and (2) It can be projected onto any size screen (from home theater setups to movie theater setups), with equal image quality.
With the advent of HDTV, DLP is a great option for reproducing high-resolution projected images.
On the industrial front, DLP is being used in large projection screen applications such as concert venues and movie theaters. Some of the first films that were released to take advantage of DLP projection technology, included: Star Wars: Episode I, Mission To Mars, Toy Story 2, Rocky and Bullwinkle, Disney's Dinosaur, and Spy Kids. Now digitally projected movies are quite common. The results are very impressive. This technology is rapidly replacing standard film projection. DLP provides a large projected image with significant brightness and enough contrast.
If you would like to see a movie projected in DLP, check your local movie listings for an announcement, it is worth the experience.
Mitsubishi manufactures rear-projection DLP sets for consumers. Projection TVs using DLP technology are quite affordable, about 1/3 to 1/2 the price of an equivalent LCD or Plasma TV of the same screen size.
Conclusion
CRT and LCD projection systems have been the mainstay in big screen and projection TV applications in both consumer and industrial settings for quite some time. While CRT-based projection systems have improved over the years, DLP technology, with its compactness, increased brightness and contrast has replaced CRT as a dominant video projection technology. However, in the separate video projector/screen market, improvements in technology and lower manufacturing costs have placed LCD video projection in a tight race with DLP in terms of image quality and popularity.
For an additional resource going into more detail on DLP technology as well as comparing the various video projection technologies, check out my two articles:
Video Projectors - What You Need To Know
Rear Projection Televisions - What You Need To Know
Do you have a DLP, CRT, or LCD video projector? Do you have more questions on this topic? Just drop in on my new Projection TV Forum.
