Monitors - How They Work?

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monitors_log.gif (2767 bytes)Monitors - How They Work??

How CRT Monitors Work

-The CRT Monitor that is most likely on your desktop is a cousin of you TV set. Of course they have come a long way since the TV as far as resolution is concerned offering 800X600 or better. Now you may think well why haven't TV's moved up to a better resolution if a computer has such good resolution? TV's are restricted to 525X700 and defined by NTSC (North American Television Standards Commission), surprised? Seems as if everything is made a standard and some bogus organization will make sure they make a buck on it. Well, now how does your monitor make the picture on the screen and do it fast?

-CRT Monitors, the beginning process of the monitor starts with a electron gun. This gun has the job of spraying a focused beam on the glass of the CRT tube, the tube is also in a vacuum. The inside of the glass tube that you are looking at is lined with a phosphorescent material that glows a specific color when excited by the electron gun. Now when the electron gun is firing it is usually through a aperture grill or mask. This mask insures the electron's from the gun hit precise points and make the picture sharper and look great. Now we know when the gun hits the material on the glass it will turn a certain color. We are working with (RGB) red, blue, and green colors that make up individual pixels. If the electron gun hits one pixel with just the right frequency of electrons we will have say a red pixel, little more frequency of electrons we move into a blue and so on. Making all these pixels match up into a image is a big task. So you are probably thinking how does this electron gun go across the screen and does it move this much?

-The electron gun has to update these pixels as much as 70 times a second. This has to be done to keep the phosphors lit. They do burn out if not updated and refreshed often. We need a faster gun then Jesse James for this action. Now, the process of updating the screen is called refresh. You probably have heard that term a few times and is in Hertz on a computer such as 75Hz. This means the monitor refreshes 75 times a second. Remember MHz in CPU's which can calculate information 500 million times a second? Not to slow is it.. Now when the monitor has to refresh a row of pixels we start on the left top side of screen. This is done from the left then goes to the right side, only to be turned off and start all over again at the next row. Now when you have a 800X600 resolution the electron ray gun has to spray 800 pixels per row and do 600 rows. Now do this 75 times a second or more. Kind cool huh? So does this gun just move back and forth from the back of the computer to paint our screen? No, usually for higher rates such as 75Hz and upwards magnetic fields are used to guide the electrons to there pixels more precisely.

-Something to take note of in a monitor. You need a good Video card in order to do this and keep up with bigger screen resolutions, vice versa. Make sure that your monitor or video card can support one another.



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