CRT: This Is Your Father's Television
CRTs are the boob tubes we all grew up with (and many of us still have). Once you understand how a CRT works, it's pretty easy to understand the other TV types and decide what kind to get.
CRT stands for cathode ray tube. A CRT TV (or computer monitor, for that matter) works by allowing a beam of electrons to flow from the negatively charged cathode (sometimes called an "electron gun") at the back of the picture tube to the positively charged front. When that beam gets to the front, it hits a phosphor coating, causing the phosphors to glow.
Electromagnets wrapped around the tube bend the cathode ray so that it sweeps a line of individual points (called pixels) across the uppermost edge of the tube. Then the magnets bend the ray so that it sweeps another line just below the first one, and so on and so on until it has "scanned" lines of glowing pixels from top to bottom. A CRT television runs through this process about 30 times per second, allowing it to show a rapid succession of images that simulates fluid motion.
Now, what about color? Color CRT TVs have three types of phosphor: one that glows red, one that glows green, and another that glows blue. Varying the intensity of the three colors in each pixel allows the TV to create images with a broad range of colors. This basic idea of mixing red, green, and blue light is the principle behind all television types.
Old as color CRT technology is (dating back to the 1950s), it remains quite good for many reasons. First of all, it's cheap. Companies have been making CRT televisions for decades, and they have gotten very efficient at it. Today, you can buy a fine traditional CRT TV, such as the 32-inch Sony WEGA KV-32FS120, for $600.
CRTs also have some display quality advantages. For one, they produce very rich colors and a deep shade of black. And the slightly "soft" look of glowing phosphor actually hides some of the static and imperfections in a television signal or even in DVDs.
CRT Disadvantages
Two big drawbacks of CRTs are size and weight--which will come as no surprise to anyone who has had to move a big TV. Cathode ray tubes are heavy. (In fact, they contain lead!) And as the screen gets wider, the tube gets deeper. Plus, the screen dimensions are limited by the difficulty of making tubes beyond a certain size. Sony makes one CRT, the KV-40XBR800, that measures 40 inches diagonally. Companies including Sharp and Toshiba stop at 36 inches. And Samsung stops at 32. So if you want a really big screen, a really thin TV, or both, you'll have to opt for one of the newer TV technologies.
A subtler drawback to CRTs is a slight flicker. With cheaper (older) CRT TVs, by the time the electron gun is scanning the bottom part of the screen, the top portion is already starting to fade. To minimize the effect, such sets interlace their images--lighting every other line first (for example, lines 1, 3, 5, and so on) then going back and filling in the missing lines (2, 4, 6...). But interlacing poses a problem with motion. If an object is moving quickly across the screen, one set of lines will appear a bit farther ahead than the other, leading to a slightly jagged or sawtooth appearance.
Luckily, today's picture tubes can scan much faster and don't need to interlace images, but interlacing is built into the traditional television broadcast standard.
So, when is a regular CRT television a good choice? I recommend it for people on a budget who watch some regular network television and an occasional DVD in a medium-size living room or den. If you're not a TV and movie fanatic, there's no sense in spending a fortune on a TV using one of the fancy newer technologies. And a good CRT will still provide nice picture quality. If space is cramped, you might do better with a medium-size LCD TV (which we'll talk about in a bit). If you have a really big room, or you're a TV lover who just wants a big screen and you don't mind spending a fair amount of cash, you'll want to look into one of the newer technologies, such as plasma.
Ad Choices