ABOUT MONITORS

VARIOUS TYPES OF MONITORS

OLD CRT MONITOR

LATEST LCD MONITOR

LATEST PLASMA MONITOR

TRANSFERENCE LCD MONITOR

DETAILS ABOUT MONITORS

Monitor is one of the primary component of visual display terminal. The monitor accepts the images converted from digital to analog form and display them on screen. The monitor looks like a TV screen as it also uses cathod ray tube inside but it is different from TV screen in the sense that a tuner circuit too along with CRT while the monitor does not contain a tuner circuit. Also the resolution of monitor is much higher as compared to TV screen.
There are different types of monitors are used, some of them are :-

1. CRT Monitors
2. LCD Monitors
3. Plasma Display Monitors.
CRT Monitors use cathod ray tube for displaying the images while the LCD Monitors use Liquid Crystal Displays. Normally all the computers use the CRT Monitors except for very small computers like Laptops and note books etc. LCD Monitors are small and easy to carry monitors because they do not use the bulky cathod ray tube. Also their power consumption is small as compared to CRT displays but still CRT display monitors are more in use. Let use have a look on both of them.
CRT Monitors: - The CRT monitors look much like a TV screen and they use cathod ray tube as its major component. The cathod ray tube is a large, bulky vacuum tube made up of metal and glass. The front side of this tube is larger as compared to back end. At the front edge of this tube a glass screen is placed and at the back side an electron gun is attached. The shape of this tube is nearly conical. The glass screen is coated with a phosphorus substance from inside. This substance produces a glow when it is bombarded with electrons.
The CRT monitor assembly is spacious as compared to laptop computers. They need substantial amount of energy for their operation and much of it is dissipated as heat. So the extra space is provided in it to prevent monitors circuitory from damaging because of heat. There are ventilation slots made in the enclosure through which the heat is allowed to escape. Another reason for this extra space is for high voltage insulation because some monitors even generate up to 30 kV during their normal operation. A monitor contains five parts which are:-
¤ Enclosure Box
¤ Cathod Ray Tube
¤ Video Drive Board
¤ Power Supply
¤ Raster Drive Board
The enclosure box contains all other parts of the monitor. At front edge the CRT is mounted and it is fixed on base of the monitor. The back side is removable and there is enough space at back side of it. Cathode ray tube is a large bulky vacuum tube made up glass and metal. Which is conical in shape. It contains a coated screen at front edge and electron gun/guns at other edge. The CRT drive board controls brightness, screen size, focus grid voltage etc. For the CRT's. It contains video amplifiers and drivers. Power supply is a hand sized assembly which converts AC into DC voltage levels required for monitor circuit. The levels are usually one or more of the ....

> +135
> +20
> +12
> +87
> +6.7
for its various parts. Raster drive contains micro controller driven circuit to operate on monitor adjustments. There are two types of CRT monitors available in the market depending on the colors used for display. They are :-
> Monochrome Monitor
> Color Monitor

LCD Monitors: - The LCD monitors are different from CRT monitors. It contains a fixed number of pixels unlike CRT screen. These pixels can create pixels of different sizes. It gives a very good output at a particular resolution only. Another problem with them is they use transmissive display while a CRT display uses an emissive display. So its output can be viewed only at an angle. Though they are prone to flicker which the CRT's are not and there size is small with easy transportation but CRT's pad more in use and LCD are limited to small computers like laptops and notebooks. Rest about LCD's is beyond the scope of this book.
A monitor can work in one of the modes called: -
¤ Text Mode
¤ Graphics Mode

Plasma Display Monitors: - A plasma display is the most advanced technology based device. These monitors display a very good quality of picture which is sharp from every angle. Plasma is a gas mad of free flowing ions and electrons and it is a central element of flourscemu light. The basic idea of plasma display is to make an image by illuminating very small coloured flourescent light and can produce image in any colour by their varying intensities.
Plasma panel display is constructed by filling region between two glass plates with gas. A series of horizontal and vertical electrons, placed on the front and rear glass panels, respectively, are used to light up individual points in the gas.

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