Plasma TVs, those slim and elegant screens with the big presence, are finally readily available to consumers. But why did it take so long? Why did older TVs need all that bulk at the back to create a much smaller picture? That big bump at the back of a traditional television is a cathode ray tube. An electronic beam is sent from the neck of the tube to scan the face of the tube. As it rapidly passes across the face, it lights up pixels. Pixels (picture elements) are groups of red, blue and green phosphors. The television image is made up of these lighted phosphors. Plasma televisions don't need a cathode ray tube. Their technology is more closely related to that used in a fluorescent light bulb. The display area is made up of hundreds of thousands of tiny cells. Within each cell there are two glass panels separated by a very narrow gap. A neon-xenon gas in plasma form is injected into that gap and the cells are sealed. The gas is electrically charged at specific intervals when it receives a television signal. The charged gas then strikes the pixels, making the red, blue and green phosphors light up. By varying the pulses of current flowing through the cells, the intensity of each subpixel color can be increased or decreased to create all the colors in the spectrum. Since there is no need for an electronic beam, the plasma TV can be thin enough--generally less than four inches--to hang on a wall. | 
