VIDEO DISPLAY DEVICES :-

Primary o/p device of any graphic s/m : video monitor

The operation of most of the monitor is based on cathode ray tube.

REFRESH CATHODE RAY TUBE:-

• Electron gun emits electron which passes through focussing and deflection s/m and then direct the beam towards the phosphor coated screen.
• Phosphor-emits small spot of light at each position contacted by electron beam.
• Light emitted by phosphor fades quickly.
• One way to keep phosphor glowing is to redraw the picture quickly redirecting electron beam back over same points

This type of display is refresh CRT.

PRIMARY COMPONENTS OF ELECTRON GUN :-

• HEATED METAL CATHODE
• CONTROL GRID