OUTPUT DEVICES

Mr. S. Neebar

Computer Output Devices An output device is any electronic equipment connected to a computer that is used to transfer data out of the computer in the form of text, images, sounds, or other media

Monitors Monitors, commonly called as Visual Display Unit (VDU), are the main output device of a computer. It forms images from tiny dots, called pixels that are arranged in a rectangular form. The sharpness of the image depends upon the number of pixels.

There are two kinds of viewing screen used for monitors.

• Cathode-Ray Tube (CRT)

• Flat- Panel Display

Cathode-Ray Tube (CRT) Monitor The CRT display is made up of small picture elements called pixels. The smaller the pixels, the better the image clarity, or resolution. It takes more than one illuminated pixel to form whole character, such as the letter ‘e’ in the word help. A finite number of characters can be displayed on a screen at once. The screen can be divided into a series of character boxes - fixed location on the screen where a standard character can be placed. Most screens are capable of displaying 80 characters of data horizontally and 25 lines vertically. There are some disadvantages of CRT: • Large in Size • High power consumption

Flat-Panel Display Monitor The flat-panel display refers to a class of video devices that have reduced volume, weight and power requirement in comparison to the CRT. You can hang them on walls or wear them on your wrists. Current uses of flat-panel displays include calculators, video

games,

monitors, laptop computer,

graphics display.

LCD Monitors

Liquid Crystal Display (LCD) or, as they are also known, Liquid Crystal Diode is one of the most popular display technologies currently. LCD monitors are lightweight, compact, occupy less space, consume low power and are available in a reasonable price.

LED Monitors Light Emitting Diodes (LED) monitors use light

emitting diodes that acts as a performance booster in the monitors. Basically LED monitors are the LCD monitors with a LED backlight to power up the LCD panel. It means that LEDs are placed behind or around the LCD panel to enhance the luminosity and video definition of the monitor screen.

LED Monitors • LED TVs have better colour contrast and

brightness than other type of TV technology. The display is bright enough to watch in any light. They also draw less power (up to 40% less) than both LCD or plasma displays, and the energy efficiency helps to compensate for the technology’s fairly high cost. They also do not use mercury in their construction, so are more environmentally friendly.

• The greatest drawback of an LED TV is its cost. Because the technology is new, it is more expensive than its competition. Additionally, LED TVs still sometimes suffer from the “dead pixel” issue that haunts LCD screens.

Plasma Monitors Plasma TV technology uses the same basic

principle of CRT TV insofar as it relies on excited phosphor atoms to produce each pixel of a TV picture. However, instead of using a CRT, a plasma TV screen lights each pixel with a hot, ionized gas, consisting of atomic nuclei and electrons. This method allows every pixel in the display to be turned on or off at the same time and the absence of a CRT means that plasma TVs can be much thinner and lighter than their CRT counterparts.

Projectors A data projector is a device that takes the text

and images displaying on a computer screen and projects them on a larger screen. There are LCD projectors, and the new Digital Light Processing (DLP) projectors that can be used for a variety of purposes, including 3D output. Some cellular phones have even designed with projector capability.

Printers • Printers are the most commonly used output

device. A printer produces text and graphics on a physical medium. The printed information is called a hard copy, or printout, and it can be printed in landscape or portrait orientation

Printers

There are two types of printers:

• Impact Printers

• Non-Impact Printers

Impact Printers The impact printers print the characters by striking them on the ribbon which is then pressed on the paper. Characteristics of Impact Printers are the following: • Very low consumable costs • Very noisy • Useful for bulk printing due to low cost • There is physical contact with the paper to

produce an image These printers are of two types: • Character printers • Line printers: prints one line at a time

DOT MATRIX PRINTER

• A dot‐matrix printer produces printed images when tiny wire pins on a print head mechanism strike an inked ribbon. Character printers are the printers which print one character at a time.

DOT MATRIX PRINTER Advantages

• Inexpensive

• Widely Used

• Other language characters can be printed

Disadvantages

• Slow Speed

• Poor Quality

Non-Impact Printer

• Non-impact printers print the characters without using ribbon. These printers print a complete page at a time so they are also called as Page Printers.

• These printers are of two types

• Laser Printers

• Inkjet Printers

Characteristics of Non-impact Printers

• Faster than impact printers.

• They are not noisy.

• High quality.

• Support many fonts and different character size.

Laser Printers • These are non-impact page printers. They use

laser lights to produce the dots needed to form the characters to be printed on a page.

• Advantages

• Very high speed

• Very high quality output

• Give good graphics quality

• Support many fonts and different character size

• Disadvantages

• Expensive.

Inkjet Printers Inkjet printers are non-impact character printers based on a relatively new technology. They print characters by spraying small drops of ink onto paper. Inkjet printers produce high quality output with presentable features. They make less noise because no hammering is done and these have many styles of printing modes available. Colour printing is also possible. Some models of Inkjet printers can produce multiple copies of printing also. Advantages • High quality printing • More reliable Disadvantages • Expensive as cost per page is high • Slow as compared to laser printer

THE END