Projection Tv

Projection TV Technology And Additional Features

As with nearly every aspect of our lives, our television sets are being improved with updated technology and additional features. Understanding all of the terms in today's TV environment can be a challenge.

In the area of rear projection TVs, the set works because an image is projected from the rear of the unit to the screen. The image is created from a signal received from some source, whether internal or external. An interior signal would be from a DVD, VHS tape or memory chip. An exterior signal is the information from a cable company, a satellite provider or a TV station that broadcasts a signal from a local tower.

Cable and satellite service is already offered in high definition and in a digital format. And by 2009 all stations that broadcast a signal will have to be digital. But no fears, most all current TVs in use should be just fine. TVs that receive input from either cable or satellite are not impacted. It will only be TVs that receive a broadcast signal from a local tower that will need to be digital compatible. And the industry has had several years to get ready for this change, so all models made in recent years, including projection TVs, are already equipped with a digital tuner.

What happens inside the projection TV does vary depending on the technology being used. Some projection TVs use CRT or Cathode-ray tube as the way of making the image on the screen. This technology has been in use since the early days of TV and is used in conventional TVs. Projection TVs with CRT are easy to spot because they are big and bulky. The technology needs the extra depth to beam light from three separate tubes. There is one tube for each color used in TVs: red, green and blue. These three colors are combined to create the final image. CRT projection TVs are more reliable and less expensive than the newer versions. The picture quality is very good. The major detractors for consumers are the large size and heavy weight.

The next technology up the price ladder is LCD or liquid crystal display. LCD requires a single lamp and a color wheel to create the images on the screen. The resulting picture is bright and the units are much slimmer than the bulky CRT versions. The technology does not produce high quality black levels which can leave the resulting image looking dull. The sets can also have what is referred to as the screen door effect. When the screen is viewed close up, the image appears as though it were being seen through a screen door.

DLP (digital light processing) uses a spinning color wheel, a bulb and nearly a million tiny mirrors to create an image. The mirrors receive the image from the bulb as it shines through the color wheel. Then they bounce the image unto the screen. DLP does a better job of producing rich black levels, much closer to the CRT quality. The bulb does need to be replaced after about 6000 hours of use and some viewers report a rainbow effect on the screen. This happens when the human eye registers an overload of one color.

LCoS or liquid crystal on silicon is consistently rated best for technology. The liquid crystals take the place of the mirrors used in DLP models. The sets are the thinnest available and the rainbow effect and screen door effect seen on other formats are not a problem.