[1] : The Free On-line Dictionary of Computing (27 SEP 03)

cathode ray tube
     
         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.
     
        1994-11-17
     
     
see also:
vdu monitors vacuum tube raster pixel persistence 
dot pitch resolution interlace 

Cathode Ray >> C Words
Cathode Ray, definition of term: Cathode Ray
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Cathode Ray Tub >> C Words
Cathode Ray Tub, definition of term: Cathode Ray Tub
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Cathode >> C Words
Cathode, definition of term: Cathode
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Capillary Tube >> C Words
Capillary Tube, definition of term: Capillary Tube
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Bronchial Tube >> B Words
Bronchial Tube, definition of term: Bronchial Tube
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Boob Tube >> B Words
Boob Tube, definition of term: Boob Tube
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