![]() Because they broadcast separate signals for the different colors, all of these systems were incompatible with existing black and white sets. Each frame encoded one color of the picture, and the wheel spun in sync with the signal so the correct gel was in front of the screen when that colored frame was being displayed. Most experimental systems broadcast entire frames in sequence, with a colored filter (or " gel") that rotated in front of an otherwise conventional black and white television tube. At the time, a number of systems were being proposed that used separate red, green and blue signals ( RGB), broadcast in succession. This variation is sometimes referred to as a slot mask.ĭevelopment Color television Ĭolor television had been studied even before commercial broadcasting became common, but it was not until the late 1940s that the problem was seriously considered. For television use, modern displays (starting in the late 1960s) use rectangular slots instead of circular holes, improving brightness. 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.Ī red, a green, and a blue phosphor are generally arranged in a triangular shape (sometimes called a " triad"). The other two guns do the same for the red and green dots. 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 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. 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. 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. Shadow masks are made by photochemical machining, a technique that allows for the drilling of small holes on metal sheets. Both of these technologies are largely obsolete, having been increasingly replaced since the 1990s by the liquid-crystal display (LCD).Ī 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. All early color televisions and the majority of CRT computer monitors used shadow mask technology. The other approach is the aperture grille, better known by its trade name, Trinitron. 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. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |