Output is the result of processes that are done on
the computer. An output device receives information
from the computer and translates it from machine
language to a form that humans can read or so that
another machine can read the information. Output
that is readable by the user can be categorized into
two categories: hard copy or soft copy. Hard copy is
a relatively permanent form of output that can be
read immediately or stored for later use, such as
paper. Printers are the most common hard copy
output devices. Soft copy is a transient form of
output, for example, text on a screen display. It is
lost when the computer is turned off unless it is
saved in the main memory or on a disk
NAMES OF SOME OUTPUT DEVICES ARE GIVEN BELOW: PRINTERS
 MONITORS
 SPEAKERS
 HEADPHONES
 PLOTTER
 PROJECTORS
A most convenient and useful method
by which the computer can deliver
information is by means of printed
characters. Printers can be divided into
two distinct categories :
 IMPACT PRINTERS: In these printers,
there is a mechanical contact between
the print head and paper.
 NON IMPACT PRINTERS: In these
printers, there is no mechanical contact
between the print head and paper.
i.
Drum Printers- It consist of cylindrical
drum on which characters are
embossed for each & every print
position on line. Drum is rotated at
very high speed. Character is printed
by striking hammer against embossed
character on surface.
ii. Chain Printers- It has characters
engraved in type assembled on a
chain. With the rotation of band,
hammer is activated when desired
character comes in front of it.
iii. Dot Matrix printer- print head contains
a vertical array of pins. As the print
head moves across the paper, selected
pins fire against the ribbon. The more
pins the print head has the better will
be the printing quality.
1. Electromagnetic printers- they use magnetic recording
techniques. Required output is written on a drum
surface, which comes into contact with the magnetic
powder that adheres to the charged areas. The powder
is then pressed onto the paper.
2. Inkjet printers- It uses a continuous stream of ink
drops to print characters on paper. The print head
contains tiny nozzles that spray drops of ink on the
paper. The quality is good because the characters are
formed by dozens of tiny ink drops.
3. Thermal Printers- It uses a special heat-sensitive
coated paper. When a spot on the paper passes under
the print head, it gets heated. This turns the coating in
that area black, producing the image of the character
on the paper.
4. Laser Printers- They print one page at a time. The
output image is written on a copier drum with the help
of an electrically charged light beam. These attract the
toner ink particles which are then deposited on and
DISPLAY UNITS
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LIQIUD CRYSTAL
DISPLAY (LCD)
CATHODE RAY TUDE
(CRT)
DIGITAL
MONITORS
VIRTUAL DISPLAY
MULTIPLE MONITORS
LIQIUD CRYSTAL DISPLAY

Passive LCD produce poor contrast, slow
response, and other image defects.
These were used in most laptops until the mid
1990s .
Thin Film Transistor LCD‘s give much better
picture quality in several respects.
size
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CATHODE RAY TUBE
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Raster scan computer monitors, which produce
images using pixels .
Television sets were used by most early
personal and home computers, connecting
composite video to the television set using a
modulator.
DIGITAL
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Early digital monitors
are sometimes known as
TTL’s because the
voltages on the red,
green, and blue inputs
are compatible with
TTL logic chips .
They are capable of
displaying 32-bit
grayscale at 1024x768
resolution .
MONITORS
VIRTUAL DISPLAY
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Screenshot of the Spaces environment under
Mac OS X.
Much software and video hardware support the
ability to create additional, virtual pieces of
desktop, commonly known as workspaces.
MULTIPLE MONITORS
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Two Apple flat-screen
monitors used as an
extended desktop .
More than one monitor can
be attached to the same
device.
The more sophisticated of
the two, extension allows
each monitor to display a
different image, so as to
form a contiguous area of
arbitrary shape.
Computer speakers, or multimedia speakers,
are external speakers, commonly equipped with
a low-power internal amplifier. Computer
speakers range widely in quality and in price.
The computer speakers typically packaged with
computer systems are small plastic boxes with
mediocre sound quality. Some of the slightly
better computer speakers have equalization
features such as bass and treble controls,
improving their sound quality somewhat. The
internal amplifiers require an external power
source, known as a 'wall-wart'. More
sophisticated computer speakers may have a
'subwoofer' unit, to enhance bass output, and
these units usually include the power amplifiers
both for the bass speaker, and the small
'satellite' speakers
SPEAKERS
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LOUDSPEAKER
DRIVER TYPES
WOOFER
ENCLOSURES
DIGITAL SPEAKERS
LOUDSPEAKER
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A loudspeaker, speaker, or
speaker system is an
electromechanical
transducer that converts an
electrical signal to sound .
most loudspeaker systems
require more than one
driver, particularly for high
sound pressure level
WOOFER
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A woofer is a driver that
reproduces low
frequencies .
Additionally, some
loudspeakers use the
woofer to handle middle
frequencies, eliminating
the mid-range driver .
ENCLOSURES
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Most loudspeaker systems
consist of drivers mounted
in an enclosure, or cabinet
The role of the enclosure is
to provide a place to mount
the drivers and to prevent
sound waves from the back
of a driver from interfering
destructively
DIGITAL SPEAKERS
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Digital speakers have been the subject of
experiments by Bell Labs as far back as the
1920s.
The term "digital" or "digital-ready" is often
used for marketing purposes on speakers or
headphones .
Headphones are a pair of small
loudspeakers, or less commonly a single
speaker, with a way of holding them close to
a user's ears and a means of connecting
them to a signal source such as an audio
amplifier, radio or CD player. They are also
known as earphones, ear buds, stereo
phones, headsets or, informally cans. In the
context of telecommunication, the term
headset is used to describe a combination of
headphone and microphone used for twoway communication, for example with a
telephone
A plotter is another hard
copy output device that
reproduces graphic images
on paper using a pen that is
attached to a movable arm.
Multi coloured pen can also
be used. Plotters are slow
devices. The graphics they
produce are uniform and of
very good quality. Plotters
can be divided into 4 types
Drum plotter, Micrographic
plotter, Inject plotter,
Flatbed plotter
A video projector takes a video signal
and projects the corresponding image
on a projection screen using a lens
system. All video projectors use a very
bright light to project the image, and
most modern ones can correct any
curves, blurriness, and other
inconsistencies through manual
settings. Video projectors are widely
used for conference room
presentations, classroom training, home
theatre and live events applications.
Projectors are widely used in many
schools and other educational settings,
connected to an interactive white
board to interactively teach pupils