Metal sheet with hundreds of thousands of holes, used in CRTs to correctly align colors
This article is about cathode ray tube (CRT) displays. For shadow masking in 3D computer graphics, see shadow mapping.
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Shadow maskClose-upIn-line (left) and triad (right) shadow maskShadow mask-based CRT in close-up
The shadow mask is one of the two technologies used in the manufacture of cathode-ray tube (CRT) televisions and computer monitors which produce clear, focused color images. The other approach is the aperture grille, better known by its trade name, Trinitron. All early color televisions and the majority of CRT computer monitors used shadow mask technology. Both of these technologies are largely obsolete, having been increasingly replaced since the 1990s by the liquid-crystal display (LCD).
A shadow mask is a metal plate punched with tiny holes that separate the colored phosphors in the layer behind the front glass of the screen. Shadow masks are made by photochemical machining, a technique that allows for the drilling of small holes on metal sheets. Three electron guns at the back of the screen sweep across the mask, with the beams only reaching the screen if they pass through the holes. As the guns are physically separated at the back of the tube, their beams approach the mask from three slightly different angles, so after passing through the holes they hit slightly different locations on the screen.
The screen is patterned with dots of colored phosphor positioned so that each can only be hit by one of the beams coming from the three electron guns. For instance, the blue phosphor dots are hit by the beam from the "blue gun" after passing through a particular hole in the mask. The other two guns do the same for the red and green dots. This arrangement allows the three guns to address the individual dot colors on the screen, even though their beams are much too large and too poorly aimed to do so without the mask in place.
A red, a green, and a blue phosphor are generally arranged in a triangular shape (sometimes called a "triad"). For television use, modern displays (starting in the late 1960s) use rectangular slots instead of circular holes, improving brightness. This variation is sometimes referred to as a slot mask.
The shadowmask is one of the two technologies used in the manufacture of cathode-ray tube (CRT) televisions and computer monitors which produce clear...
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cathode-ray tube (CRT) televisions and computer displays; the other is the shadowmask. The first patented aperture grille televisions were manufactured under...
metal masks (FMMs) made by photochemical machining, reminiscent of old CRT shadowmasks, are used in this process. The dot density of the mask will determine...
offered brighter images than conventional color television systems using a shadowmask, but a host of development problems kept it from being widely used in...
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beam on the correct color, a problem RCA solved with their shadowmask system. The shadowmask is a thin metal foil with small holes photoetched into it...
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producing a different stream of electrons. Each stream travels through a shadowmask where the electrons will impinge upon either a red, green or blue phosphor...
typical shadowmask RGB CRT or two phosphor layers (so-called "penetration color"). Atari used the term color quadrascan to describe the shadow-mask version...
The Apple Performa Plus Display is a color 14″, 13″ viewable shadowmask CRT that was manufactured by Apple Inc. from September 14, 1992, until July 18...
red-green-blue-masked phosphor areas, dictated by a mesh grid called the shadowmask, it would require a difficult calibration step to be aligned with the...
keyboard, mouse, an external modem and either a dot-29 or dot-39 pitch shadowmask CRT monitor. Professional models, in contrast, were sold à la carte with...
these, RCA's teams quickly started focusing on the shadowmask system. In July 1938 the shadowmask color television was patented by Werner Flechsig (1900–1981)...
precision instruments, clocks, seismic creep gauges, color-television tubes' shadow-mask frames, valves in engines and large aerostructure molds. One of its first...
never used commercially due to the much better images generated by RCA's shadowmask system. Nevertheless, Geer's patent was awarded first, and RCA purchased...
it was enormous, expensive, impractical, and dropped as soon as the shadowmask system was successful. However, the Triniscope idea was used commercially...
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