cathode-ray tube

cathode-ray tube, special-purpose electron tube in which electrons are accelerated by high-voltage anodes, formed into a beam by focusing electrodes, and projected toward a phosphorescent screen that forms one face of the tube. The beam of electrons leaves a bright spot wherever it strikes the phosphor screen. To form a display, or image, on the screen, the electron beam is deflected in the vertical and horizontal directions either by the electrostatic effect of electrodes within the tube or by magnetic fields produced by coils located around the neck of the tube. Some cathode-ray tubes can produce multiple beams of electrons and have phosphor screens that are capable of displaying more than one color. Cathode-ray tubes are used in television sets, computer monitors, automated teller machines, oscilloscopes, and radar displays.

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cathode-ray tube (CRT)

In a colour-television tube, three electron guns (one each for red, green, and blue) fire electrons …

(credit: Encyclopædia Britannica, Inc.)

Vacuum tube that produces images when its phosphorescent surface is struck by electron beams. CRTs can be monochrome (using one electron gun) or colour (typically using three electron guns to produce red, green, and blue images that, when combined, render a multicolour image). They come in a variety of display modes, including CGA (Color Graphics Adapter), VGA (Video Graphics Array), XGA (Extended Graphics Array), and the high-definition SVGA (Super Video Graphics Array).