CRT - cathode ray tube.

   Surface covered with phosphor dots of one or more colors.

   Phosphors arranged as dots (little islands).
     The size and closeness of dots determines maximum actual resolution. 
     Electronics may take higher resolution and adjust it.`
     
   Stream of electrons (from gun) strikes phosphor causing it to glow.
      Color requires 3 guns, red, green, blue 

   Magnetic circuits bend stream to traverse screen.

   Screen draw in lines across surface, working down the screen.

   Phosphors glow for limited time. 
     Fade fast enough so that there is no ghost the next time image is drawn.
       Good for moving images, not good for static images (text).
     
     Fade slow - better for static images but moving images blur.
       oscilliscope (and radar screens) use slow fade to store data on screen.
 
    see wikipedia : refresh rate

   Data has to be fed fast enough to cover all lines on screen before human
     eye/mind notices picture faded.

   Higher the resolution, the more data needed.

   Interlacing (every other line) allows more lines without increasing 
     data/screen but may be noticeable if image not moving.

   525 lines x 60 Hz (TV standard, interleaved) flicker is detectable by 
     most people.  On TV, image is moving, so flicker not noticed.

   Original motion pictures changed 24 frames a second but actually 
     illuminated the frame multiple times.

     Because whole picture displayed,  brain blends images so you don't 
     see flicker.

   70-80 Hz flicker noticed by < 10% 
 
   100 Hz, very few can see this. Quickly changing images blur less.

   Because of the flexibility of bending an electron stream and the fact
     that the pixels actually emit light, changing the resolution on a
     crt while maintaining a quality display is easier than doing so on
     a lcd display.
 
  640*480*8bit = 30,720 bytes/screen * refresh rate. (VGA)
  1024*768*24bit = 2,359,296 bytes/screen * refresh rate. (XGA)
  1600*1200*32bit = 7,680,000 bytes/screen * refresh rate. (UXGA)
  1920*1080*24bit = 6,912,000 bytes/screen * refresh rate (HD1080)

  Dot-pitch determines how small discrete edges can be displayed.

  Properties of CFT

  - Burn-in - when certain pixels are used more often than others, they begin
     to deteriate over time. 
     * The reason for screen savers and turning off video.

  + high contrast, color and light/dark
  + no native resolution, although some designs may favor certain resolutions.
  + can support very high refresh rates, no blurring.
  + great viewing angle.

  - larger displays require larger devices.
    - longer in depth (front to back).
    - very heavy.
  - minimum size 7"
  - dangerous to repair
  - large number of toxic elements in construction.
  - images not as sharp as lcd

LCD