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cathode-ray tube
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Diagram of a color television picture tube using the shadow-mask technique, showing red, green, and blue electron beams from electron guns passing through an aperture grille to strike phosphor-coated glass, with labeled parts and a close-up of the grille structure. Figure 10: Flying spot camera system.
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Allen B. DuMont
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Diagram of a color television picture tube using the shadow-mask technique, showing red, green, and blue electron beams from electron guns passing through an aperture grille to strike phosphor-coated glass, with labeled parts and a close-up of the grille structure.
In a colour-television tube, three electron guns (one each for red, green, and blue) fire electrons toward the phosphor-coated screen. The electrons are directed to a specific spot (pixel) on the screen by magnetic fields, induced by the deflection coils. To prevent “spillage” to adjacent pixels, a grille or shadow mask is used. When the electrons strike the phosphor screen, the pixel glows. Every pixel is scanned about 30 times per second.

cathode-ray tube

technology
Also known as: Braun tube, CRT
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History

cathode-ray tube (CRT), 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).

This article was most recently revised and updated by William L. Hosch.