What is output device ?? Output device

What is output device ?

Output devices are electromechanical device that accepts data from a computer and translates them into a form suitable for use by outside world (user). The output devices receive information from the computer and provide them to the users. The computers send information to the output devices in binary coded form. The output devices convert them into a form which can be used by the users such as printed form or display on the screen. The commonly used output devices are monitors, printers, speaker, plotters etc. Output devices generate two kinds of output. They are soft copy output and hard copy output. 

Differences between soft copy output and hard copy output devices 

Softcopy output	Hardcopy output
1. Soft copy output is displayed in audio or visual form.	1. Hard copy output is displayed in printed or recorded form.
2. Soft copy output is temporary in nature.	2. Hard copy output is permanent in nature.
3. Soft copy output is expensive.	3. Hard copy output is cheaper.
4. Example: Monitor, Speaker	4. Example: Printer, Plotter

 

A. Soft-Copy Output 

A soft-copy output is not produced on a paper or some material that can be touched and carried for being shown to others. They are temporary in nature. The output produced in visual or audio form by monitors or speaker is soft copy output. When the electricity goes off, the output is also invisible to the users. Some of the soft copy output devices are discussed below: 

i. Monitor

Monitors are the most popular output devices used today for producing soft-copy output. Monitors are similar with the TV screen . A monitor is associated with a keyboard and together they form a video display terminal (VDT) . The keyboard is used for giving input to the computer and the monitor is used to display the output from the computer. The basic types of computer monitor are :

Monochrome monitors:

Monochrome means information displayed in one color such as white, green, black, blue, amber or gray on a different color background usually black. These monitors are usually used to display text only where we don't need to see color graphics. Some handheld computers use monochrome monitors to save the battery power. Monochrome monitors are almost outdated now.

Color Monitors:

Color monitors are the types of output device, especially one of the monitor used to display output in different colors i.e from 16 colors to millions of colors. Today, most of the personal computers use color monitors. Now-a-days the color monitors are of three main  types. They are : CRT Monitor, LCD Monitor and LED Monitors.

CRT (Cathode Ray Tube ) Monitors

CRT monitors work much like television screen and are used with personal computers.  It displays the data and information received from the computer memory. It can display the alphanumeric characters and graphs. An electron beam is produced by the electron gun located at the back portion of the cathode ray tube. The electron beam is directed towards the front of the CRT screen. A coating of phosphor material is made on the inner surface of the screen. The phosphor emits light when it is struck by the electron beam on the screen. This causes the visibility of the characters or graphics. 

LCD (Liquid Crystal Display) Monitors

LCD monitors are thinner, lighter than CRT monitors and are used commonly with portable computer systems like notebook computers. With gradual reduction in price of LCD flat panel monitors ,  they are used increasingly with non-portable desktop computer systems. They are also preferred because they occupy less space.

LED (Light Emitting Diode) Monitor

The LED monitors are the advance application of LCDs. They are far better than the LCD technology. Due to the better techniques used in the LED monitors, these monitors are very accurate in their color display . The contrast ratio of LED monitors is much better than that of the LCD monitors.

ii. Speaker

A speaker is an audio response soft copy output device that produces audio output from the computer system. The output is temporary, soft-copy output. A speaker produces audio output by selecting an appropriate audio from a set of pre recorded audio responses. When audio output is to be produced, the computer selects the appropriate sound from the set of pre-recorded sounds. The selected sound is converted back into analog from and then routed to a speaker to produce the audio output..

B. Hard copy output

A hard-copy output devices is produced on a paper or some material that can be touched and carried for being shown to others. They are permanent in nature. Output produced by printers or plotters are hard-copy output.

i. Printers:

Printers are the most popular output devices used today for hard-copy output. They provide information in a permanent readable form. They produce printed output of results, programs and data. The printers are classified as to how they print. According to this, the printers are classified as impact and non-impact printer.

a. Impact Printers:

Impact printers use electro-mechanical mechanism that causes hammers or pins strike against a ribbon and paper to print the text. Impact printer produce loud sound during printing. So they are also called noisy printers. Dot Matrix printer, Daisy Wheel printer, Drum Printer etc are the examples of impact printer.

Dot-Matrix Printer

Dot -Matrix printers are character printers that print one character at a time. They form characters and all kinds of images as a  pattern of dots. A dot=-matrix printer has a print head that moves horizontally (left to right and right to left) across the paper . Print head contains an array of pins that can be activated independent of each other to extend and strike against the inked ribbon to form patterns of dots on the paper. To print a character the printer activates the appropriate set of pins as the print head moves horizontally.

Drum Printers

Drum printers are line printers that print an entire line at a time. It consists of a solid cylindrical drum with characters embossed on its surface in the form of circular bands. Each band consists of all printing characters supported by the printer in its character set. Total number of band is equal to the maximum number of characters that can be printed on the line. The drum printer has a set of hammers mounted in front of the drum in a manner that an inked ribbon and paper can be placed between the hammers and the drum. A character is printed at a desired position by activating the appropriate hammer  when the character embossed on the band at the print position passes below it.

b. Non-Impact Printer :

Non-impact printers do not use electromechanical printing output device head to strike against ribbon and paper. They use thermal, chemical , electrostatic laser beam or inkjet technology for printing the text. Non-impact printers are faster than the impact printers. They do not produce sound while printing. Ink Jet printer and laser printers are the examples of non-impact printers.

Inkjet printers

Inkjet printers are non-impact printers because they print by spraying ink on the paper. They are characters and all kinds of images by spraying small drops of ink on a paper. The print head of an Inkjet printer contains up to 64 tiny nozzles that can be heated up selectively in a few microseconds by an integrate circuit resistor. To print a character the printer heats the appropriate set of nozzles as the print head moves horizontally.

Laser Printers

Laser printers are very fast non-impact page printers that print one page at a time. Main components of laser printers are laser beam source, mirror , a photoconductive drum and a toner. To print a page of output, the laser beam is focused on the electro statically charged drum by spinning the surface of the drum in a manner to create the pattern of characters and images to be printed on the page. The toner sticks to the drum in the places where the laser beam has charged the drum surface. The tonner is then fused permanently on the paper with heat and pressure to generate the printed output. Laser printers produce very high quality output because they form characters by very tiny ink particles. These printers give excellent graphics art quality.

Difference between Impact and Non Impact printer:

Impact printer	Non impact printer
i. Impact printers produce sound while printing.	i. Non impact printers do not produce sound while printing.
ii. Impact printers are cheaper than non impact printers.	ii. Non impact printers are more expensive than impact printers.
iii. Impact printers are slower than non impact printers.	iii. Non impact printers are faster than impact printers.
iv. Example of Impact printer:       Dot matrix printer.	iv. Example of non Impact printer:      Laser printer.

 ii. Plotters

Plotters (referred to as graphic plotter ) are the hard copy output devices. They are used to produce good quality graphics and drawings under computer's control. They use ink pen to draw drawings or graphics. Single color or multicolor pens can be used for drawings. A graph plotter takes much less time to draw anything as compared with traditional hand methods of producing drawings. A complex drawing which can take about a month by traditional hand method can be produced in less than an hour using plotters.

Communication device (Modem)

Modulator and Demodulator is communication device which is mainly used to transmit data suitable for user and computer. It is also known as input output device. It is a device by which we can connect our PC to the Internet Service Provider over the  telephone line. The role of modem in data communication is to convert the analog signals such as telephone line to digital signals (to be converted into binary format)  for data transmission and vice versa while sending and receiving data. The Modem is specially used in telecommunication and data communication.

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