Saturday, April 01, 2006
The Cathode Ray Tube Projector utilizes the old-fashioned picture tube that has been used in conventional TV sets for decades. With this type of projector, three CRTs, plus a magnifying lens, are used to cast an image onto a screen. The CRTs are used to project the primary colors, red, blue and green. This kind of projector works well to generate great contrast, very distinct blacks, and great color. Because CRT images are not scanned with an electron beam, they aren't confined to a certain pixel range and offer greater latitude when it comes to resolution display. Overall, a CRT projector gives viewers a very satisfactory, film-quality image. Unlike DLP and LCP models, CRT projectors do not have bulbs that require replacing, which saves the consumer money. Also, CRT models last for 20,000 hours - a relatively long life.
There are some drawbacks to this kind of projector. CRT models are usually pretty expensive, starting at around $10,000. They're also large, often requiring the same amount of room as a 20-inch TV set. Also, for a CRT projector to work to its maximum capability, a dark room is required.
A Liquid Crystal Display (LCD) projector utilizes clear chips made of single pixels. Light is transmitted through these chips to produce an image, which is cast onto a screen. Most LCD projectors are small and compact. They also offer great contrast and brightness. They're also affordable, starting at $1,000. A good home theater model might cost $3000.
LCD projectors can cause problems when it comes to visibility of individual pixels. If a pixel dies, or burns out, it's replaced on the screen by a black or white dot, which lessens the quality of the image. Pixels can't be fixed. After they burn out, the chip in the projector should be replaced. LCD projectors use bulbs that must be replaced every 1,000-2,000 hours. These bulbs cost a few hundred dollars, and they're easy to install.
Digital Light Processing (DLP) projectors use chips with thousands of mirrors that move quickly to produce an image. A color wheel supplies color, which is beamed off the chips as they move. The color produced with this type of projector is high-quality. There is no visibility of pixels, and the projector itself is very compact. Contrast and brightness are excellent, also.
One of the downsides to a DLP projector is what's called a rainbow effect. This can happen when a viewer sees a flash of color after looking rapidly away from the screen. As with the LCD model, the bulb has to be replaced about every 1,000-2,000 hours. Right now, the DLP projector is the most popular model being used in home theater.