Nov 9, 2012


The device through which computer display the processed result at the end of  each process is known as
output device.
Example -Monitor,Printer,Speaker, Headphone, Plotter etc.


Monitor is an important output device. It is also known as Visual Display Unit(VDU). It is use to display the processed result in a screen  from of a soft copy. Without monitor, system can't work.


There are three types of monitor -------

a>CRT(Cathode Ray Tube):  CRT stands for cathode ray tube. These are all old model monitors. Main disadvantages are heavy weight, occupy more place, high power consumption, high radiation and supports low resolution. These are all main reasons to prefer LCD or LED monitors.

b>LCD(Liquid Crystal Display):  LCD stands for liquid crystal display. The main advantage of LCDs are light weighty, occupy less place, 12 volts power consumption, low radiation and supports high resolutions.

c>LED(Light Emitting Diode):  LED stands for light emitting diode. Actually there are no differences between LCD and LED monitors, but better picture quality in LED monitors. So now all are prefer LED monitors than LCD monitors.

This is use to print the hard copy of any processed result in a page.

                    Types of printer ------- 

a. Dot-matrix printer:  These printers have print head comprising of a matrix tiny needles, typically 7 rows with 9 needles each(9*7 matrix), which hammers out characters in the form of patterns of tiny dots. The shape of each character is stored electronically in the printer. Dot-matrix printers are less expensive, faster and can print any shape of character and graphics.
INK: Ribbon.
Dot-matrix Printer

b.Ink-jet printer:  Ink-jet printers function like dot-matrix printers. They form images or characters with small dots. In these printers, dots are formed by tiny droplets of ink. The speed of these printers is up to about 270 c.p.s. they produce less noise. There are several manufacturers producing color ink-jet printers. In some of these printers, all color inks are in one cartridge. For replacing one color you have to replace all the colors but in some other color ink-jet printers, you can replace inks individually. For those who use one color predominantly, these printers are better.
INK: Cartridges.
Ink-jet printer

c. Laser printer:  In this technology, no print head move and no print hammers hit. Therefore the speed is very high and the noise is negligible. It functions like a photostat machine. A laser beam is directed across the surface of a light sensitive drum and fired as needed and image is thus recorded in the form of a pattern of tiny drops. The image is then transferred to the paper, using a special toner. Laser printers have a very high speed and level of noise is very low. The quality of the printers is very high and these printers are also useful for excellent graphic work. Their maintenance requirement is also very low.
INK: Toner Cartridges.
Laser printer



Speakers are another type of output device , which allow you to listen to voice like music and conversation with people.


Headphones are output device. They are similar to speakers, except they are worm on the ears so only one person can hear the output at a time.
Head Phones


Plotters are specialized output devices which produce high quality graphics in various colors. Some of the plotters use pens which others do not. Drum plotters and flatbed plotters both use pens. Electrostatic plotters do not in a drum plotter, the paper is mounted on the surface of a drum. As drum revolves, the plotter pens are horizontally positioned over the printing areas as the paper rotates to the correct point. The pens are dropped to the surface and moved
left and right across the paper as the drum revolves. After the image is completed, the pens are raised from the surface. In flatbed plotters, the paper is placed flat and one or more pens move horizontally and vertically across paper. Electrostatic plotters use electrostatic charges to create images with small dots on specially treated paper. The paper is run through a developer to allow the image to appear. Electrostatic plotters are faster and produce very high resolution images. Many 2 to 8 pens flatbed plotters are available for microcomputer systems. As some small drum plotters, large plotters can produce drawings up to 8*8 feet or even larger. These plotters are used with large computer systems.


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