![]() Since the late 2000s, CRTs have been largely superseded by newer "flat panel" display technologies such as LCD, plasma display, and OLED displays, which have lower manufacturing costs and power consumption, as well as significantly less weight and bulk. As a matter of safety, the face is typically made of thick lead glass so as to be highly shatter-resistant and to block most X-ray emissions, particularly if the CRT is used in a consumer product. The fact that it is evacuated makes handling an intact CRT potentially dangerous due to the risk of breaking the tube and causing a violent implosion that can hurl shards of glass at great velocity. The interior of a CRT is evacuated to approximately 0.01 pascals (9.9×10−8 atm) to 133 nanopascals (1.31×10−12 atm), evacuation being necessary to facilitate the free flight of electrons from the gun(s) to the tube's face. In all modern CRT monitors and televisions, the beams are bent by magnetic deflection, a varying magnetic field generated by coils and driven by electronic circuits around the neck of the tube, although electrostatic deflection is commonly used in oscilloscopes, a type of electronic test instrument.Ī CRT is constructed from a glass envelope that is large, deep (i.e., long from front screen face to rear end), fairly heavy, and relatively fragile. In color devices, an image is produced by controlling the intensity of each of the three electron beams, one for each additive primary color (red, green, and blue) with a video signal as a reference. In television sets and computer monitors, the entire front area of the tube is scanned repetitively and systematically in a fixed pattern called a raster. The images may represent electrical waveforms (oscilloscope), pictures (television, computer monitor), radar targets, or other phenomena.ĬRTs have also been used as memory devices, in which case the visible light emitted from the fluorescent material (if any) is not intended to have significant meaning to a visual observer (though the visible pattern on the tube face may cryptically represent the stored data). ![]() The CRT modulates, accelerates, and deflects electron beam(s) onto the screen to create the images. It contains an electron gun, and this gun shoots electrons toward the phosphorescent screen. It is used to display images on a screen. Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.The cathode-ray tube (CRT) is a vacuum tube.Britannica Beyond We’ve created a new place where questions are at the center of learning. ![]() Can display in almost any resolution and refresh rate (within the limitations of the horizontal and vertical sweep rates supported by the complete display).
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