Monitors

 

You communicate everyday with your computer via the computer's monitor. The monitor is the screen that displays the programs you are running, the images and text documents, and all sorts of other information! Unlike most other parts of your computer, the monitor does not perform any calculations or operations. Instead, it is merely responsible for conveying all of the information to you by displaying it on a screen.

Most monitors are based on the CRT, or cathode ray tube. Cathode ray tubes are glass tubes that are narrow at one end, and open up to a wide screen at another. They are the display devices of the monitors. Cathode ray tube monitors consist of three basic parts:

1. Electron Guns:
The electron guns are found at the very back of the monitor. These release a stream of electrons that produce a picture on the screen. On black and white monitors, there is only one electron gun, while color monitors have three-one for each of the three colors: red, green, and blue. Contrary to what you might think, these guns do not fire colored electrons. Rather, the electrons are fired down a tube to light up phosphors on the computer screen. The "colored" guns fire only at the colored phosphors on the screen.

The electron guns start at the upper left hand corner of your computer screen. They fire electrons left to right along the top of your screen, then they move down a line. This continues until the whole screen is finished. Your computer screen is divided into tiny sections called pixels. A pixel consists of one red, one blue, and one green phosphor dot. They line up in rows and columns to form your screen, and are so small that they appear to all be connected!




2. Steering Magnet (focusing coil):

Electron guns do not randomly shoot out electrons at the phosphor dots on your computer screen. Rather, they need some sort of direction as to which dot to light up. This is accomplished by energizing magnets that line up along the tube and direct the electrons to the correct phosphor dot.



3. Phosphor Coated Screen:

The inside of your computer screen is coated with phosphors. As stated above, there is no such thing as colored electrons, so the phosphors on the screen must be colored. There are red, green, and blue colored phosphors. One phosphor dot of each of these colors are arranged to form a triad. Triads are what make up one pixel, the smallest unit that can be displayed by your computer screen.

The phosphors on your computer screen light up and glow for a short while after they have been struck by the electron gun. This is what creates the images seen on your computer screen. For different colors, different combinations of the triads are struck, and this can create a full color spectrum! You might also notice that you can control the brightness of your computer screen. The brightness of each pixel is determined by a video data stream that is coming out of your computer's video card. The video cards are responsible for the different graphics and images your computer can use! However, because the phosphors only light up for a short while, the electron gun has to continuously redraw the image. This is known as "refreshing."

Continue on to the next section:
Liquid Crystal Displays

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