How do those little people get inside the screen?

1. Tv's translate broadcast signals into pictures and sound. The technology has been around for decades, but how does it work? The truth is that it's all a trick on your eyes. To project the moving image you see, most tv's use a cathode ray tube, or CRT. The cathode is a heated element held in a vacuum within a sealed glass "tube" inside the television set. It emits a stream of electrons (the "ray" part of the name) at the inside of the screen. The screen itself is composed of glass, coated on the inside with tiny dots or stripes of phosphor (a material that glows when exposed to energy) and a shadow mask, which is a thin metal screen with tiny holes that align to the phosphor.
2. The screen glows because of the coating of phosphor on the inside, which gives off light when the beam of electrons strikes it. The electron beam creates the image on the screen by playing across the phosphor one line at a time. Controlled by the magnetic coils inside the tube, the electrons paint across the screen from left to right faster than the human eye can see. While moving from the end of one line back to the beginning of the next, the beam turns off, to avoid leaving a trail across the screen. The electron beam paints every other line in a frame, first the odd lines, and then the even lines, all the way down the screen. This happens 30 or 60 times per second, depending on the type of tv.
3. In a black and white screen, only a single type of phosphor is used, which glows white when hit by the electrons. A color screen, on the other hand, uses three colors of phosphor: red, green and blue. The three colors are arranged in dots or stripes on the screen, and each color is activated by a separate beam of electrons. Different combinations and intensities of these three colors create what appears to be an infinite range of colors. To create a white dot, all three phosphors light up at once. To create a black dot, the electron beams simply bypass that spot and leave it dark. If you look very closely at a television screen (especially with the aid of a magnifying glass), you can see the individual colored phosphor stripes. From a distance, these stripes blend together into a seamless image. In other words, your eye is watching a single dot trace its way across the screen, one phosphor at a time. But it's going so fast, it looks like a moving image.
4. A Plasma tv works on a similar principle, lighting up a combination of red, green and blue dots to form an image. But instead of using a beam of electrons to light up phosphor bars, a plasma TV uses tiny fluorescent lights instead. This enables a screen to be flat and much wider than a traditional tube type, without being as deep. It also gives a crisper image, making the new flat-screen design much more popular now.