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 ?
EPA would require any company exporting cathode ray tubes to give the agency notice of the shipment.
Cathode ray tubes, or CRTs, are made of heavy leaded glass, which is used to block harmful X-rays produced by the tube's cathode ray guns.
LG Philips is a Hong Kong-based maker of cathode ray tubes (CRTs) used in televisions and monitors.
Sony's Bridgend plant makes the cathode ray tubes used in televisions assembled in Pencoed.
Those electronics are now banned from California landfills because the cathode ray tubes and liquid crystal display or LCD monitors contain toxic metals that can leach from dumps over time.
Nine of 30 cathode ray tubes from color computer monitors passed the standard shredded-parts test even though separate tests have shown that most of these tubes contain huge amounts of lead (SN: 11/4/00, p.
subsidiary will phase out production and marketing of cathode ray tubes for direct view color TV (CPT) by the end of April 2002.
Loosely based on a didactic timeline chronicling the history of media, Oursler's site allows visitors to explore such varied topics as ancient Egyptian modes of communication, the camera obscura, cathode ray tubes, and X-ray devices in a cross-disciplinary--and highly aestheticized--manner.
Massachusetts has become the first state to ban the disposal of computer monitors, televisions, and arcade video games containing cathode ray tubes (CRTs) in public landfills or incinerators.
Electronic Recyclers has the largest electronic recycling facility in the state that demanufactures, recycles and crushes the cathode ray tubes found in computer monitors, televisions and other types of video equipment.
United States Environmental Protection Agency (EPA) Administrator Steve Johnson has signed a rule that is designed to facilitate the recycling of devices that contain cathode ray tubes (CRTs).
It will use the UK's first laser separation technology to recycle glass from cathode ray tubes.