The cathode ray tube (CRT) is a vacuum tube containing an electron gun (a source of electrons or electron emitter) and a fluorescent screen used to view images. It has a means to accelerate and deflect the electron beam onto the fluorescent screen to create the images. The image may represent electrical waveforms (oscilloscope), pictures (television, computer monitor), radar targets and others. CRTs have also been used as memory devices, in which case the visible light emitted from the fluoresecent 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 uses an evacuated glass envelope which is large, deep (i.e. long from front screen face to rear end), fairly heavy, and relatively fragile. 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.
CRTs have largely been superseded by more modern display technologies such as LCD, plasma display, and OLED, which as of 2012 offer lower manufacturing and distribution costs.
The vacuum level inside the tube is ultra-high vacuum on the order of 0.01 Pa to 133 nPa.
A cathode ray tube is a vacuum tube which consists of one or more electron guns, possibly internal electrostatic deflection plates, and a phosphor target. 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. 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 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 diagnostic instrument.
Other articles related to "ray, cathode ray tube":
... Patent 2,455,992, filed by Goldsmith and Estle Ray Mann in 1947, describes what may be the world's first cathode ray tube based game and patent, and was inspired by ... Entitled "Cathode Ray Tube Amusement Device", the patent describes a game in which a player controls the CRT's electron gun much like an Etch A Sketch ... By connecting a cathode ray tube to an oscilloscope and devising knobs that controlled the angle and trajectory of the light traces displayed on the oscilloscope, they were able to invent a missile game ...
Famous quotes containing the words tube and/or ray:
“One of the great natural phenomena is the way in which a tube of toothpaste suddenly empties itself when it hears that you are planning a trip, so that when you come to pack it is just a twisted shell of its former self, with not even a cubic millimeter left to be squeezed out.”
—Robert Benchley (18891945)
“These facts have always suggested to man the sublime creed that the world is not the product of manifold power, but of one will, of one mind; and that one mind is everywhere active, in each ray of the star, in each wavelet of the pool; and whatever opposes that will is everywhere balked and baffled, because things are made so, and not otherwise.”
—Ralph Waldo Emerson (18031882)