Display screen are of two types these are as follows:

1. CRT Monitor: CRT monitor is the most common form of display screens, it looks like a television. It can display text and graphics.

Wording of CRT Monitor
It uses a cathode ray tube (CRT) to display an image on the screen. CRT consists of one or more guns that fire a beam of electrons, inside the screen. The screen is coated with tiny phosphor dots from inside. The beam of electrons repeatedly falls on the surface of screen. Every beam-fall takes only a fraction of a second.

Wording-of-CRT-Monitor

CRT in color monitors consists of three guns these guns generate red, green and blue (RGB) colors. The other colors are generated with the combination of these three colors.

2. Flat pane3l display: Flat-panel monitors take less space and are lightweight. These monitors use much less power than CRTs. Notebook computers use flat panel monitors. Flat panel display is made up of two plates of glass. These plates contain a substance between them. The substance is activated in different ways.

There are three types of technologies used in flat panel display screens:

I. liquid Crystal Display (LCD)

This type of display screen contains a substance called liquid crystal. The molecules of this substance line up in such a way that the light behind the screens blocked or allowed to create an image.

II. Electro Luminescent Display (ELD)

This type of display screen contains a substance that glows when it is charged by electric current.

III. Gas plasma Display

This type of display screen is similar to neon bulb. The display uses a gas that emits light in the presence of an electric current. It is more expensive technology. It is not commonly used.

LCD-monitor CRT- monitor

figure: LCD monitor                                                                      Figure: CRT monitor

Advantages of flat panel display over CRT

The advantages of flat panel display over CRT are as follows:

1. It takes less desk space.

2. It uses less energy than CRT monitor.

3. It uses liquid crystal technology.

4. Its weight is less than CRT.

5. It is used for notebook computers, PDAs, cellular phones and personal computers.

6. It does not emit harmful radiation