Cathode Ray Tube

A large vacuum tube featuring a slightly curved glass surface at one end (the screen) and an emitter of electrons on the other, which focuses and directs a stream of electrons to hit a coating of phosphors on the back side of the screen. hosphors are elements that glow a certain color when excited by electrons. As the phosphors are bombarded with electrons from the electron gun or emitter, the screen glows with an array of colors (the phosphors glow and their colored light is passed through the glass screen to the viewer). he electron beam is directed by magnetic fields created by the deflection yoke (or simply the yoke), a series of wire coils surrounding the neck of the picture tube (the far end from the screen). As the deflection yoke directs the electron beam, it scans across the screen hitting rows of phosphors and creating an image. Before the electrons actually hit the phosphors, however, they first pass through the shadow mask. he shadow mask is a perforated grille with many tiny holes for the electrons to pass through. The shadow mask prevents stray electrons from hitting phosphors other the specific ones they are aimed at. athode ray tubes are the most common type of video display. They are found in television sets and computer monitors as well as in projection televisions and front projectors. CRTs produce good color accuracy and deep blacks. They can be made in a variety of resolutions and are generally very flexible and adaptable. The primary disadvantages of CRTs are their size and weight. CRT displays cannot be made into flat panels and weigh increasingly more as their size increases (try lifting a 35 inch direct view television – it is very heavy and deep, the two primary disadvantages of CRTs).