A Brief Overview Of Rear Projection Technology

By Allan Wilson

Even though Plasma and LCD flat panel televisions are popular for their stylish sets and many number of people opt for these sets, because of high cost they can not be affordable. So, the rear projection is becoming craze for its lower pricing, but high performance in the television market. Rear projection systems are similar to traditional televisions. They display images on the back of a screen rather than the front, and the projector is completely inside the television itself. The term rear-projection means that the image is projected and reflected onto the screen area from behind the screen as compared to traditional video and film projection where the projector itself is placed in front of the screen, such as in a movie theater.

Elements of rear projection television

A rear projection TV basically consists of five elements namely projector technology used to produce a video image, the type of lens combination used to magnify the projected image, a mirror to reflect the projected image, the screen on which the reflected image being produced, and the box to be used to put all the other four elements.

Rear projection technologies

1. CRT – CRT stands for Cathode Ray Tube. This technology is the most basic and common in all televisions. It uses considerably smaller tubes compared to a standard television. These tubes produce an image in the same way as a standard television produces by firing electrons at a phosphor-coated screen. A CRT technology consists of a color CRT with red, green, and blue phosphors; a black and white CRT and a spinning color wheel that adds the color; and three small CRTs one each for red, green and blue. CRTs can produce excellent high resolution images with the proper video processing circuitry, CRT size, and lens combination. The demerit is that these televisions are usually large and consume lot of space and the design is complicated as everything needs to be perfectly aligned for best quality.

2. LCD – LCD stands for Liquid Crystal Display. It uses different technology compared to CRT. It uses a powerful light to be passed through an LCD chip containing the video pixels. This creates a grey scale image. A series of mirrors that split the light into red, green and blue beams is used to add colors. Each beam passes through a separate LCD and a lens collects all the three beams and projects the image on the screen. Merits are compact and portable and they use less power to run and also good contrast and brightness capabilities. Demerits are due to its production and design and also high of chips.

3. DLP – DLP stands for Digital Light Processing. It uses a small, rectangular device made up of microscopic mirrors called Digital Micromirror Device (DMD) to create high quality images. The mirrors point toward or away from a projection lens, depending on whether the corresponding pixel needs to be light or dark. Most DLP rear-projection sets have one DMD and a spinning, multicolored wheel that adds color.

Merits

- Screen size starts from 42 inches and go up from there.
- Excellent picture quality.
- Not susceptible to burn-in.
- Durability.

Demerits

- Lamp replacement can be expensive.
- These are of big size, heavy and occupy a lot of floor space.

Allan Wilson owns and operates http://www.rear-projection-tvs.com where you can find some great information about rear projection tvs. Rear Projection Tvs
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