CATHODE RAY TUBES - (CRTs)
The CRT has been widely used as a display device for over 75 years; however it was not applied to computer displays until the 1960s. The most common early uses were oscilliscopes, radar, and television.
CRT is basicly a vaccuum tube with the face coated with a chemical - phosphor - which gives off light when struck by energic electrons. The electron beam is generated in the back of the tube by an "electron gun" and aimed at the desired place on the face of the tube by either electrostatic, or more commonly, electromagnetic fields. To produce a color display three types of phosphor - one for each primary color - are used and a mix of primary colors produced.
