Cathode Ray Tube(CRT)

Cathode Ray Tube (CRT) is a display technology that uses a very special vacuum tube inside which the visuals are produced whenever an electron moves and hits the phosphorescent surface. Phosphors consist of materials of high purity and activators and they can convert electron energy into light energy. When electric current is applied, the electric energy beam is being swept horizontally across the phosphor.

The energy beam keeps sweeping continuously and at an incremental pace. Display of images is made possible through a series of horizontal lines created by turning the beam on and off as it sweeps across the phosphor. The current in the sweeping electric beam generates the required luminance level for the picture.

Three factors control the kind of resolution you see on a CRT monitor: (1) the screen dot pitch (2) the size of the electron beam, (3) the video amplifier's bandwidth. The dot pitch indicates the diagonal distance between like colored dots on a display screen. Typically, the dot pitch of a chathode ray tube is approximately 0.8/0.9 mm. Resolution and brightness of the display unit is controlled by increasing and decreasing the dot pitch. It is one of the most important characteristics that determine the quality of display screens. The size of the electron beam is also for picture quality. Higher CRT guns can deliver higher resolution. Normal TVs have 7" CRT guns and they can resolve around 700 lines of resolution. Higher end TVs with higher CRT guns could resolve upwards of 900 lines of resolution. Also the higher the bandwidth of the video amplifier, the better is the quality of the pictures displayed.

Ten years back, CRT was the most dominant technology that reigned supreme in the display technology market. But with the advent of newer display technologies like Liquid Crystal Display (LCD), Plasma Display Panel (PDP) etc. its market share has fallen to a great extent. But still CRT is the reference standard for all other technologies which proves its quality and durability.