OUTPUT DEVICES

The devices that are used ot get output from the system are called as output devices. These devices are used to get back the information from the computer and then display it to the users.

EXAMPLES

Some common output devices are monitors, printers, disk drives etc.

MONITOR

Monitor is also called as video display unit.It is the most popular output device.A monitor displays information on the screen of a picture tube similar to the one used in a television set.

PIXELS

Picture or text that appears on the screen is formed by tiny dots called as picture elements or pixels.These pixels determine the quality or resolution of the image.Greater is the number of pixels higher will be the resolution and better will be the image quality.

TYPES OF MONITORS

There are two types of monitors:

Black and White Monitors (Monochrome)

Colored Monitors

PRINTER

It is a device which is used to produce human readable computer output on a paper.The printers are one of the most useful output devices for use with a computer.Printers are sued to produce hard copy or permanent record of computer’s output.

CLASSIFICATIONS

The printers are classified in to two main categories depending upon the type of print mechanism:

Impact Printers

Non-Impact Printers

IMPACT PRINTERS

Produces characters by using pins. Impact printers work just like typewriters.

FEATURES

Print on may paper types.

Noisy in nature.

Slow printing speed in PPM (Page per Minute).

TYPES

Dot MatrixPrinters

Daisy Wheel Printers

Line Printers

DOT MATRIX PRINTERS

It is an impact printer.

Use pins for printing.

A normal dot matrix printer has speeds varying from 50 to 600 characters per second.A standard width printer prints 80 characters per line.

DAISY WHEEL PRINTERS

Impact printers.

Use the wheel for printing.

The daisy wheel printer uses a flat disk or wheel with petal.The wheel rotates to bring the desired character into position.A character is formed when hammer strikes the petal under it.

LINE PRINTERS

They are called the line printers as they print one complete line at a time. Line printers are also impact printers. May be further divided in to drum printers and band or chain printers. Some of these produce over 3000 lines per minute.

NON-IMPACT PRINTERS

Non-Impact printers are developed to produce a printer image with out striking the paper.

Faster in nature.

QuieterProduce good quality output.

Allow different colors

TYPES

Electrostatic Printers

Electro Thermal Printers

Ink Jet Printers

Laser Printers

ELECTROSTATIC PRINTERS

They are high speed printers.

A charged image is formed on paper by electric field. This paper ispassed through an ink fog. The paper is then passed through the heater rollers for fixing the image.

ELECTRO THERMAL PRINTERS

Low cost.

Require special heat sensitive waxy paper.

Uses colored waxes and heat to produce image by burning dots on a special paper.

INK JET PRINTERS

Use tiny nozzles for printing instead of pins.

Have good quality printing.

Pretty suitable for home purpose.

Have low cost.

They form characters on the paper by spraying small electricallycharged droplets of ink through tiny nozzles. Generally they have four inks with whom color printing is also possible.

LASER PRINTERS

Produce excellent quality outpu.

High speed (typically 4 to 32 pages per minute).

These printers use laser and electro photographic technology.The image is transferred to the printer that activates a laser beam. The laser beam duplicates the image on a rotating drum and forms a charged image on it. The image is transferred on the paper that passes between the drum and positively charged wire.

PLOTTERS

They are hard copy output device similar to printer.They are used for producing large drawings or images such as construction plans for buildings, architectural drawings etc.

TYPES

Drum Plotter

Flatbed Plotter

DRUM PLOTTER

Use one or more pens that move on a sheet of paper to produce images.Used to produce continuous output.

It consists of a paper drum on which paper moves and a pen to draw output. Paper is placed on drum that rotates back and forth to produce images. Paper moves vertically while pen does horizontal movements.

FLATBED PLOTTER

Use one or more pens that move on a sheet of paper to produce images.

They are less expensive.

Used in small computers.

Paper is fixed on a rectangular flatbed. Pens of different colorsmove on the surface. Pens can be raised or lowered onto the paperduring drawing. Microprocessor selects the desired pen. Pens move on Xand Y axis.

CD WRITER

CD Writer is an output device. A CD-R (Compact Disk Recordable) is written by the CD writers.CD Writers offer a low cost alternative in making softcopies by saving large amount data on CDs.The data can’t be changed once written on a disk. It can only be read from the disk.A CD-ROM can save large amount of data up to 700 Mbytes.

DISK DRIVES

The device that drives/runs the disks (floppy, hard disk & CD’s) are called as disk drives.

HARD COPY

Computer printed output on the paper is called as “hardcopy”.It can’t be changed and it is a permanent record.The material printed on paper sheets, like books, newspapers is the hard copy.

SOFT COPY

Data stored on the disks is often referred to as a “softcopy” and can be accessed and altered easily.The computers output that appears on the monitor is called “softcopy”.Changes can be made easily in it. It is easy to organize.