cathode ray tube

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cathode ray tube

(hardware)
(CRT) An electrical device for displaying images by exciting phosphor dots with a scanned electron beam. CRTs are found in computer VDUs and monitors, televisions and oscilloscopes. The first commercially practical CRT was perfected on 29 January 1901 by Allen B DuMont.

A large glass envelope containing a negative electrode (the cathode) emits electrons (formerly called "cathode rays") when heated, as in a vacuum tube. The electrons are accelerated across a large voltage gradient toward the flat surface of the tube (the screen) which is covered with phosphor. When an electron strikes the phosphor, light is emitted. The electron beam is deflected by electromagnetic coils around the outside of the tube so that it scans across the screen, usually in horizontal stripes. This scan pattern is known as a raster. By controlling the current in the beam, the brightness at any particular point (roughly a "pixel") can be varied.

Different phosphors have different "persistence" - the length of time for which they glow after being struck by electrons. If the scanning is done fast enough, the eye sees a steady image, due to both the persistence of the phospor and of the eye itself. CRTs also differ in their dot pitch, which determines their spatial resolution, and in whether they use interlace or not.
References in periodicals archive ?
Eventually, the amount of CRT "cullet" - the crushed remains of trashed cathode ray tubes that are recycled - will outstrip demand, and the toxic screens will end up in landfills, explained Jeremy Gregory, a research scientist at the Massachusetts Institute of Technology and a co-author of a new paper on CRT recycling.
Bridgend plant to specialise in making cathode ray tubes.
State officials estimate some 6 million televisions and monitors containing cathode ray tubes are stored in people's garages and closets.
Laptop computers contain much less lead than cathode ray tubes do.
In July 2001, Hitachi announced that it would withdraw from business of cathode ray tubes for PC monitors.
The largest recycler of electronic waste in the State of California, Fresno-headquartered Electronic Recyclers is licensed to de-manufacture, recycle and crush the cathode ray tubes found in computer monitors, televisions and other types of video equipment.
With 35,000sqft of processing space, the factory will have the capacity to recycle 500,000 cathode ray tubes a year - around five per cent of the total UK annual volume of redundant tubes.
principally manufactures and distributes world-wide cathode ray tubes in the replacement market for use in television sets and data display screens, including computer monitors, monitors, medical monitoring equipment and various other data display applications.
The ERA facility de-manufactures, recycles and crushes cathode ray tubes found in computer monitors, televisions and other video equipment.
The Bridgend plant makes the cathode ray tubes, which are used in the colour televisions assembled at Pencoed.
The San Jose based company's plan is to manufacture a flattened television using a form of field emission display technology it calls ``thin CRT'' for the cathode ray tubes that power today's TVs and desktop computer monitors.
Founded in 1904 and formerly known as City Metals, AMI offers an array of recycling service for metals, plastics, glass and electronic scrap, including the handling of cathode ray tubes (CRTs) within computer and TV monitors.