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shadow-mask 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.
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shadow-mask tube

television
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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 shadow-mask tube is a type of color cathode-ray tube (CRT) used in older televisions. It features a thin steel plate with thousands of precisely aligned holes positioned behind the phosphor screen. Three electron beams, each corresponding to a primary color (red, green, or blue), pass through these holes. The shadow mask directs each beam to strike only the phosphor dots of its designated color, preventing them from hitting adjacent colors. This precise alignment allows the three primary color images to mix in the viewer's perception, creating a full-color image. While effective, shadow-mask tubes had limitations, including energy loss as electrons hit the mask and the need for extreme precision in alignment. An alternative, the aperture grille, was later developed to improve brightness.1

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2 Britannica Sources
  1. television - Shadow masks and aperture grilles
  2. shadow mask

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