Information to Printer and Monitor
OUTPUT DEVICES
Following
are few of the important output devices, which are used in Computer Systems:
Monitors
Graphic Plotter
Printer
Monitors
Monitor commonly called as Visual
Display Unit (VDU) is 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 the pixels.
There are two kinds of viewing screen
used for monitors:
1. Cathode-Ray Tube (CRT)
2. Flat-Panel Display
1.
Cathode-Ray Tube (CRT) Monitor
In the CRT, display is made up of
small picture elements called pixels for short. 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:
C Large in
Size
C 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 compared to the CRT. You can hang them on walls or
wear them on your wrists. Current uses for flat-panel displays include
calculators, video games, monitors, laptop computer, graphics display.
The flat-panel display are
divided into two categories:
Emissive Displays
- The emissive displays are devices that convert electrical energy into light.
Example are plasma panel and LED (Light-Emitting Diodes).
Non-Emissive Displays - The Non-emissive displays use optical effects
to convert sunlight or light from some other source into graphics patterns.
Example is LCD (Liquid-Crystal Device)
Printers
Printer
is the most important output device, which is used to print information on
paper.
There are two types of
printers:
1. Impact
Printers
2. Non-Impact
Printers
Impact Printers
The
printers that print the characters by striking against the ribbon and onto the
paper, are called impact printers.
Characteristics
of Impact Printers are the following:
Very
low consumable costs
Impact
printers are 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:
1. Character
printers
2. Line
printers
Character
Printers:
Character Printers are printers, which print one
character at a time.
These
are of further two types:
1. Dot
Matrix Printer (DMP)
2. Daisy
Wheel
Dot Matrix Printer
In
the market, one of the most popular printer is Dot Matrix Printer because of
their ease of printing features and economical price. Each character printed is
in form of pattern of Dot's and head consists of a Matrix of Pins of size(5*7,
7*9, 9*7 or 9*9) which comes out to form a character that is why it is called
Dot Matrix Printer.
Advantages
Inexpensive
Widely
Used
Other
language characters can be printed
Disadvantages
Slow
Speed
Poor
Quality
Daisy
Wheel
Head is
lying on a wheel and Pins corresponding to characters are like petals of Daisy
(flower name) that is why it is called Daisy Wheel Printer. These printers are
generally used for word-processing in offices which require a few letters to be
send here and there with very nice quality representation.
Advantages
More reliable than DMP's
Better quality
The fonts of character can be easily
changed.
Disadvantages
Slower than DMP's
Noisy
More expensive than DMP's
Line
Printers
Line
printers are printers, which print one line at a time.
These
are of further two types:
Drum
Printer
Chain
Printer
Drum Printer
This
printer is like a drum in shape so it called drum printer. The surface of drum
is divided into number of tracks. Total tracks are equal to size of paper,
i.e., for a paper width of 132 characters, Drum will have 132 tracks. A
character set is embossed on track. The different character sets available in
market are 48 character set, 64 and 96 characters set. One rotation of drum
prints one line. Drum Printers are fast in speed and prints between 300 to 2000
lines per minute.
Advantages
Very
high speed
Disadvantages
Very
expensive
Characters
fonts can not be changed
Chain
Printer
In
this printer, chain of character sets are used so it called Chain Printers. A
standard character set may have 48, 64, 96 characters.
Advantages
Character
fonts can easily be changed.
Different
languages can be used with the same printer.
Disadvantages
Noisy
Do
not have the ability to print any shape of characters.
Non-impact
Printers
The
printers that print the characters without striking against the ribbon and onto
the paper are called Non-impact Printers. These printers print a complete page
at a time, 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.
Gives
good graphics quality.
Supports
many fonts and different character sizes.
Disadvantage
Expensive.
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. 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
