MBA
Subject Name : IT Skills
UNIT 1(conceptual frame work)
Hardware:
(b). Output Devices: Definition
- What does Output Device mean?
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.
Following
are some of the important output devices used in a computer.
(1).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
(a).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 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
(b). 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, and graphics display.
The
flat-panel display is divided into two categories −
·
Emissive Displays − Emissive displays are devices that convert electrical
energy into light. For example, plasma panel and LED (Light-Emitting Diodes).
·
Non-Emissive Displays − Non-emissive displays use optical effects to convert
sunlight or light from some other source into graphics patterns. For example,
LCD (Liquid-Crystal Device).
Printers
Printer
is an output device, which is used to print information on paper.
There are
two types of printers −
- Impact Printers
- Non-Impact
Printers
(1). 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 −
- 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
(1 a). Character
Printers
Character
printers are the printers which print one character at a time.
These are further divided into two types:
1(a.1)Dot Matrix Printer(DMP)
1(a.2).Daisy Wheel
1(a.1). 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
- Inexpensive
- Widely Used
- Other language
characters can be printed
Disadvantages
- Slow Speed
- Poor Quality
1 (a.2). 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
- More reliable
than DMP
- Better quality
- Fonts of
character can be easily changed
Disadvantages
- Slower than DMP
- Noisy
- More expensive
than DMP
(1 b). Line Printers
Line
printers are the printers which print one line at a time.
These are of two types −
- Drum Printer
- Chain Printer
1.(b.1). 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
- Very high speed
Disadvantages
- Very expensive
- Characters fonts
cannot be changed
1.(b.2). 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
- Character fonts
can easily be changed.
- Different
languages can be used with the same printer.
Disadvantages
- 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
- Faster than
impact printers
- They are not
noisy
- High quality
- Supports many
fonts and different character size
2.(a). 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
- Good graphics
quality
- Supports many
fonts and different character size
Disadvantages
- Expensive
- Cannot be used
to produce multiple copies of a document in a single printing
2.(b). 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
- High quality
printing
- More reliable
Disadvantages
- Expensive as the
cost per page is high
Slow as compared to laser printer
