Television and Radio |

For the past 75 years, the vast majority of televisions have been built around the same technology: the cathode ray tube (CRT). In a CRT television, a gun fires a beam of electrons (negatively-charged particles) inside a large glass tube. The electrons excite phosphor atoms along the wide end of the tube (the screen), which causes the phosphor atoms to light up. The television image is produced by lighting up different areas of the phosphor coating with different colors at different intensities

Cathode ray tubes produce crisp, vibrant images, but they do have a serious drawback: They are bulky. In order to increase the screen width in a CRT set, you also have to increase the length of the tube (to give the scanning electron gun room to reach all parts of the screen). Consequently, any big-screen CRT television is going to weigh a ton and take up a sizable chunk of a room.

A new alternative has popped up on store shelves: the plasma flat panel display. These televisions have wide screens, comparable to the largest CRT sets, but they are only about 6 inches (15 cm) thick. In this article, we’ll see how these sets do so much in such a small space.

If you’ve read How Television Works, then you understand the basic idea of a standard television or monitor. Based on the information in a video signal, the television lights up thousands of tiny dots (called pixels) with a high-energy beam of electrons. In most systems, there are three pixel colors — red, green and blue — which are evenly distributed on the screen. By combining these colors in different proportions, the television can produce the entire color spectrum.

The basic idea of a plasma display is to illuminate tiny, colored fluorescent lights to form an image. Each pixel is made up of three fluorescent lights — a red light, a green light and a blue light. Just like a CRT television, the plasma display varies the intensities of the different lights to produce a full range of colors.

For years, people have heard that watching a movie on a high-definition (HD) set is like looking out a window. The picture is sharper, clearer and more detailed than anything you’ll see on an older, standard-definition (SD) set. It’s supposed to be a revolution on par with the jump from black and white to color.

But after all that hype, the experience of watching a brand new HDTV can be a little anticlimactic. If you just plug it in and start watching, you might be disappointed with what you see. The picture might look pretty good but seem brighter or more unnatural than it did in the store. Or, it might be pixelated, distorted or fuzzy and not look good at all. Why does this happen? HDTVs are supposed to be better than old, analog TVs for two reasons:

• HDTVs can use digital signals made of ones and zeros rather than analog signals made of fluctuating waves. Digital signals aren’t prone to static, interference or ghost images like analog signals are. They do a better job of carrying the information that makes up the picture.
• HDTVs have a higher resolution than analog sets. They can display images with far more detail than traditional TVs can.

Fortunately, it’s easy to get better performance from your HDTV. All it takes is a few minutes to configure everything correctly and a little knowledge about what kinds of programs will look best.