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television picture 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. Side-by-side comparison of standard-definition TV (SDTV) and high-definition TV (HDTV) aspect ratios using an image of an airplane. The SDTV screen is 4 units wide by 3 units tall, while the HDTV screen is 16 units wide by 9 units tall. Both screens show dashed rectangles indicating the safe action area (90 percent) and safe title area (80 percent) within the frame.
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television picture tube

instrument
Also known as: receiver tube, television 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.
colour television picture tube At right are the electron guns, which generate beams corresponding to the values of red, green, and blue light in the televised image. At left is the aperture grille, through which the beams are focused on the phosphor coating of the screen, forming tiny spots of red, green, and blue that appear to the eye as a single colour. The beam is directed line by line across and down the screen by deflection coils at the neck of the picture tube.

A cathode-ray tube (CRT) is a vacuum tube that generates images by striking a phosphorescent surface with electron beams. CRTs can be monochrome, using a single electron gun, or color, typically employing three electron guns to create red, green, and blue images that combine for a full-color display.1

The television screen is housed within a glass plate at the wide end of the funnel-shaped CRT. The screen itself is coated with phosphors, materials that emit light when hit by high-speed electrons. In color CRTs, these phosphors are arranged in dots that glow red, blue, and green. At the opposite end, electron guns generate and direct beams of electrons. These beams are controlled by the television's signal, varying the number of electrons to adjust brightness. The beams are accelerated and focused onto the screen, creating a bright scanning spot that forms the image.2

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
4 Britannica Sources
  1. cathode-ray tube
  2. television - Electron guns
  3. television - Basic structure
  4. television - Electron tubes

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