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Before reading this howto, I highly recommend looking at any of the CRT articles published by www.howstuffworks.com. While this site contains all sorts of technical yummies, their articles on TVs and PC monitors are particularly tasty.

TVs, arcade monitors, and PC monitors are all Cathode Ray Tubes (CRT). The crude drawing above illustrates the basic operation of a Cathode Ray Tube display. A "gun" located at the back of a CRT shoots a set of electron beams towards a phosphor coated screen. When the phosphors are struck by electrons, they give off visible light. The gun that shoots the electron beams is called an "electron gun," and it typically shoots three tightly grouped electron beams. Each beam is dedicated to a type of phosphor that gives off a different color of light when struck, red, green, and blue (or RGB for short). These three primary colors can be added together to create the full visible spectrum. From the lit RGB triad below we can see that blue and green come together to create cyan, and that red and green come together to form yellow, and that red, green, and blue come together to create white, the list goes on, and on. By varying the number of electrons dedicated to each color phosphor, the electron gun can create any visible color. Black is the only exception which, of course, is created by the absence of any light (i.e. electrons).

In the days of yore, monitor phosphors were arranged much like they are above, in a triad formation. Many monitors today, however, use a grill type layout instead (pictured below).

CRTs use magnetic fields to steer / deflect the electron beams. In the theoretical CRT model pictured above, what we are basically looking at is a snap shot in time. The electron gun located at the back of the tube is shooting a set of electron beams past two deflecting magnetic fields. One magnetic field controls the horizontal deflection, the other controls the vertical deflection. By timing the potential of these two fields, the electron beams can be directed in a controllable path across the CRT's phosphor coated screen.

Today's CRTs can manipulate the electron beams at an amazing speed, at a speed usually measured in micro seconds. However, when CRTs first emerged in the late 30's, in the form of a TV, the speed with which the electron beams could be directed was comparatively slow. PC monitors are now up to six times faster than the first TVs ever made.

Many of the first arcade games ever made used vector CRTs, games like Asteroids. Vector CRTs direct the electron beams as a series of programmable lines called vectors. Unlike most CRTs, these lines don't have to follow a raster pattern.

Vector CRTs not only produced very vivid, bright graphic displays, but they also inspired the world's first 3D games. Atari released several enormously popular 3D games in the early 80s, including Battlezone, Tempest, and Star Wars, all of which used vector CRTs.

While vector CRTs produced bright colorful games, they severely limited the complexity of drawable images (images had to be drawn as a series of lines). Eventually, they fell out of favor with game developers and by the mid 80's had all but disappeared from production lines. While tremendously successful at one time, vector CRTs were ultimately displaced by the more flexible raster CRT. Now-a-days, only the grooviest arcade rooms feature vector game cabinets, as they are quite rare.

So what are raster CRTs? Well, chances are you are viewing this website on one. But even if you aren't, I'm sure you've seen one before. Most TVs and all Multisync PC monitors are raster CRTs.

While there are many variations to a grill type layout, they all strive towards the same goal, a display that contains more phosphor. Essentially, a grill type layout includes much of the horizontal space consumed by a traditional triad shadow mask. Pictured above is a Sony Trinitron aperture grill layout. Notice how much more phosphor it contains per square area over a traditional triad shadow mask layout. While Sony pioneered the first grill layouts, most CRT manufacturers now use them, albeit a hybrid of some sort.

Pictured above is a Triad Shadow Mask - Trinitron hybrid type layout. Wellsgardner's D9200 uses a layout like the one above, as do most modern arcade monitors and TVs.

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