OUTPUT DEVICE

An output device is any device used to send data from a computer to another device or user. Most computer data output that is meant for humans is in the form of audio or video. Thus, most output devices used by humans are in these categories. Examples include monitors, projectors, speakers, headphones and printers.

Devices that are used to receive the output of processed data by the computer in the form of display, print, audio and video that user can understand and use it.

Output of processed data can be divided into two classes:

Hard copy

Output that is in the form of print document, which can be read directly, long last and permanently stored. E.g. A word document containing text and images printed by the printer on a paper.

Hard Copy Devices: printers, fax machine, photographic output devices etc.

Soft Copy

Output that is in the form of metallic or audio form, which is cannot be read directly by the user. E.g. A collection of music files and folders on a CD.

Accordingly, the output devices are classified as hard copy devices and soft copy devices.

Soft Copy Devices: monitors, data projectors, speakers etc.

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 four kinds of viewing screen used for monitors.

CRT (Cathode Ray Tube)

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 a 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

LCD (Liquid Crystal Display)

A liquid crystal display (LCD) monitor is a computer monitor or display that uses LCD technology to show clear images, and is found mostly in laptop computers and flat panel monitors. This technology has replaced the traditional cathode ray tube (CRT) monitors, which were the previous standard and once were considered to have better picture quality than early LCD variants.

With the introduction of better LCD technology and its continuous improvement, LCD is now the clear leader over CRT, in terms of color and picture quality, not to mention capabilities for large resolutions. Also, LCD monitors may be made much more cheaply than CRT monitors.

LED (Light Emitting Diode) monitor

LED Display (light-emitting diode display) is a screen display technology that uses a panel of LEDs as the light source. Currently, a large number of electronic devices, both small and large, use LED display as a screen and as an interaction medium between the user and the system. Modern electronic devices such as mobile phones, TVs, tablets, computer monitors, laptops screens, etc., use a LED display to display their output.

Plasma monitors

A plasma display is a type of flat panel display that uses plasma, an electrically charged ionized gas, to illuminate each pixel in order to produce a display output. It is commonly used in large TV displays of 30 inches and higher. Plasma displays are often brighter than LCD displays and also have a wider color gamut, with black levels almost equaling "dark room" levels.

Plasma displays are also known as gas-plasma displays.

Printer

Printer is an output device, which is used to print information on paper.

There are two types of printers

• Impact Printers
• Non-Impact Printers

Impact Printers

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

1. Very low consumable costs
2. Very noisy
3. Useful for bulk printing due to low cost
4. There is physical contact with the paper to produce an image

These printers are of two types

• Character printers
• Line printers

Character Printers

Character printers are the printers which print one character at a time.

These are further divided into two types:

• Dot Matrix Printer (DMP)
• Daisy Wheel

Dot Matrix Printer

In the market, one of the most popular printers is Dot Matrix Printer. These printers are popular because of their ease of printing and economical price. Each character printed is in the form of pattern of dots and head consists of a Matrix of Pins of size (5*7, 7*9, 9*7 or 9*9) which come out to form a character which is why it is called Dot Matrix Printer.

Advantages of Dot Matrix Printer

1. Cheap
2. Widely Used
3. Other language characters can be printed

Disadvantages of Dot Matrix Printer

1. Slow Speed
2. Poor Quality

Daisy Wheel

Head is lying on a wheel and pins corresponding to characters are like petals of Daisy (flower) which is why it is called Daisy Wheel Printer. These printers are generally used for word-processing in offices that require a few letters to be sent here and there with very nice quality.

Advantages of Daisy Wheel

1. More reliable than DMP
2. Better quality
3. Fonts of character can be easily changed
4. Disadvantages
5. Slower than DMP
6. Noisy
7. More expensive than DMP

Line Printers

Line printers are the printers which print one line at a time.

These are of two types

• Drum Printer
• Chain Printer

Drum Printer

This printer is like a drum in shape hence it is called drum printer. The surface of the drum is divided into a number of tracks. Total tracks are equal to the size of the paper, i.e. for a paper width of 132 characters, drum will have 132 tracks. A character set is embossed on the track. Different character sets available in the market are 48 character set, 64 and 96 characters set. One rotation of drum prints one line. Drum printers are fast in speed and can print 300 to 2000 lines per minute.

Advantages of Drum Printer

1. Very high speed
2. Disadvantages
3. Very expensive
4. Characters fonts cannot be changed

Chain Printer

In this printer, a chain of character sets is used, hence it is called Chain Printer. A standard character set may have 48, 64, or 96 characters.

Advantages

1. Character fonts can easily be changed.
2. Different languages can be used with the same printer.
3. Disadvantages
4. Noisy

Non-impact Printers

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

These printers are of two types −

• Laser Printers
• Inkjet Printers

Characteristics of Non-impact Printers

1. Faster than impact printers
2. They are not noisy
3. High quality
4. Supports 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

1. Very high speed
2. Very high quality output
3. Good graphics quality
4. Supports many fonts and different character size

Disadvantages

1. Expensive
2. Cannot be used to produce multiple copies of a document in a single printing

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. Color printing is also possible. Some models of Inkjet printers can produce multiple copies of printing also.

Advantages

1. High quality printing
2. More reliable
3. Disadvantages
4. Expensive as the cost per page is high
5. Slow as compared to laser printer