資料來源 : Free On-Line Dictionary of Computing

cathode ray tube
     
         (CRT) An electrical device for displaying images by
        exciting phosphor dots with a scanned electron beam.  CRTs are
        found in computer {VDU}s 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)