Home / Tech / Computer Hardware
How they work


Cathode Ray Tube (CRT) monitors are made up of three basic parts:

Electron guns - In color CRTs, there are three guns. One for red, one for green, and one for blue. They fire electrons down a vacuum tube to light up phosphors on the screen (we'll get to that in a minute). Even though the name suggests that the electron guns are color (red gun, green gun, blue gun), they do not actually fire colored electrons. What each gun does, is to fire electrons only at its respectively colored phosphors on the screen.

Steering magnet (focusing coil) - Once an electron has been fired from the guns, there needs to be a way to steer or focus it onto the phosphor it needs to light up on the screen. This is done by energizing magnets along the tube to deflect the electron away from the tube walls and at the target phosphor. This is pretty complicated in that there are extremely high tolerances involved. After all, an electron is very small and is moving extremely fast. Without steering, you would have only one bright dot right in the middle of your screen. The speed at which the steering can manipulate the electrons determines your refresh rate. The refresh rate is very important, as it directly affects how fluid and flicker-free your screen will appear. More on refresh rates after I explain phosphors.

Phosphor coated screen - This is the part of your monitor you see every day, with exception to the fact that you are looking at it from the outside. On the inside, the screen is coated with phosphors which glow for a short duration after being struck with energy. The amount of time it glows after being struck is called persistence). If you remember, I said there are three electron guns. Because electrons aren't colored, the phosphors must be. That means for every pixel (picture element) on the screen, there are three phosphors (red, green and blue), arranged in what is called a triad. The closeness (density) of these triads determines your monitors dot pitch in millimeters (you usually see these represented as .28, .26, .25 etc., and I'll get into this in a little bit.)

Intro Refresh rates
leftbutt.gif (1704 bytes) ritebutt.gif (1709 bytes)


pcwizess.jpg (8520 bytes)

* PCWize Award Winners *
Click either button to see the winners of these awards.

pcwizeww.jpg (8540 bytes)
Copyright 1997-2009 Leif Gregory. TB Community | privacy policy | home | write me | advertise | about